Rear Differential Speed Sensor above is mistakenly replaced because of a code for the Transmission Output Speed Sensor in the pictures below.
Top and Side View of Transmission Output Speed Sensor and installed on Left Side of Transmission Tail-shaft.
This is another inside baseball type post concerning auto and truck repair. The first picture is of the Rear Differential Speed Sensor which is mistakenly replaced because of a code involving the Transmission Output Speed Sensor located in the left side bottom of the transmission tail-shaft. The three pictures below the one of the Differential Speed Sensor are of the Transmission Output Speed Sensor and location on a 1999 Dodge Ram 1500 pickup truck with 3.9L engine and three speed automatic transmission without overdrive. It came in with a check engine light on and intermittent stalling when slowing from freeway speeds into traffic. The code was straight forward – PO720 – Output Speed Sensor Circuit. The dealer stocks six of these. They are a common failure item. I am doing this post because the speed sensor on the differential in the first picture is often mistakenly replaced for the Transmission Output Speed Sensor code. Replacing the one on the rear differential will not get rid of the code or the problem.
I have had a number of Do It Yourself customers change the wrong speed sensor after getting a free code read at a parts store. This is mostly for their benefit because I don’t get any laughs out of people parts changing the wrong part on their vehicle, especially in these tough times. The Transmission Output Speed Sensor number on this particular vehicle and many others in the late nineties and early 2000’s is Mopar #04800879. They are not all the same so removing the sensor on the affected vehicle and jotting down the number is the best course to follow.
NOTE: Here's a quick diagnostic check for major problems or governor transducer and wiring faults. I won't explain where any of the ports are because each person attempting this check should have the proper equipment, safety cautions, and manuals:
NOTE: Here's a quick diagnostic check for major problems or governor transducer and wiring faults. I won't explain where any of the ports are because each person attempting this check should have the proper equipment, safety cautions, and manuals:
For checking a transmission similar to the one mentioned in the above post to tell if
the problem is in the transmission or the wiring is to put a pressure gauge on the
governor port and start the motor. You then pull the case connector and put the
transmission in drive. You should see main line pressure and the transmission should go into
3rd gear. If you see no pressure then you know that the problem is in the unit
and the transmission needs replaced. If you have pressure and the transmission goes to
3rd gear then you have to look at the wiring and governor valves.
That’s all for this update, but if you’re appreciative of the information, here is a link to my new novel COLD BLOODED for Nook and Kindle or check my Amazon page for my other novels. If you’re kind enough to read it and like it, please review it on the site you purchase it from. Thank You! Every little bit helps my writing gig. :)
267 comments:
«Oldest ‹Older 201 – 267 of 267Without scanner data I can't tell you, Darryll. The output speed sensor on the transmission can cause a problem like you describe, but so can the solenoid pack or the governor pressure transducer. Without doing basic pressure checks and scanner diagnosis, everything is a guess. You didn't say what it was the dealer erased or if you know whether it has returned. Taking it into a transmission shop for testing may be your best bet now. If you decide to parts change the OP sensor on the transmission make sure you use a Chrysler OEM sensor and not an aftermarket one.
Bernard, First I would like to say thank you for your hard work and dedication on this site. I have came to it several times during the last couple of months trying to figure out something with my dodge. with that said...I have a 2005 Dodge Ram 1500 4WD. When I purchased the truck 2 years ago, the rear speed sensor went out. I replaced and had no problems since until Feb. 2012. Same problem came up, engine light, truck didnt want to shift, high RPMS, etc. I changed out the same ABS Sensor again. Speedometer went wacky, ABS Lights on and idle all kinds of messed up. I took sensor back to purchase place, replaced again and Truck ran perfect for 3 days. Then back to original problems. I went through this 3 more times; the longest great running time being 1 week. I then got the truck to a dodge dealership and they were no help at all. They said buy mopar part and all should be fine. They have never heard of such a problem. I asked them if there could short or something, if they would check it, they said waste of time and money. I cant understand or believe this, but was the answer I received. I bought mopar ABS sensor and it lasted 3 weeks now. Today, engine light back on, truck not shifting and when stop with any quickness or pressure, the truck will die. The idle is off again. I replaced the sensor again and will install it tonight, and sure the truck will run perfect again for 2 days or so...but I would like to find out what is throwing the sensors out! The codes the truck threw this time are PO 700 and PO876. Which are same codes it has thrown everytime.
The dealer is right about only using a Mopar sensor, L. As to the recurring problem, my best guess is you disturb something in the wiring each time you mess with it, thereby fixing it temporarily. You could be losing continuity in the pigtail connection itself. If you don't want to take it in for diagnosis, or ohm out your electrical harness for faults, the only thing I can suggest is checking all visible parts of the harness carrying the wires to the sensor for chaffing, and install another pigtail connector.
I have a 2002 dodge stratus that is in limp mode. I have replaced the input speed sensor and the tss. my speedometer still works fine. thats why i haven't replaced the output speed sensor. the only code that comes up is the p0700 general transmission code. should i go ahead and replace the output speed sensor?
The output speed sensor will normally set a code, Michael. Chrysler has had a lot of problems with their Transmission Control Modules, including bad new ones right out of the box. The PO700 code usually points to a module problem, especially if accompanied by a PO605 Internal Rom Error Code, but sometimes just a PO700 Code. If you want to try something before getting it checked out, the output speed sensor can't hurt anything, but I'd sure like to read about it if it actually fixes a PO700 code.
well, i'll give it a shot. i just don't think the car is worth dumping $400 into it. Every shop around here wants to charge me $50 just to read the tcm codes. if all else fails, at least the car is worth $250 in scrap metal. lol
Well, replacing the output speed sensor solved nothing. So, I'm with you on this one. Has to be the TCM. Anyone want to buy a 2002 Dodge Stratus that needs a TCM?
Michael, you still have the option of having a good transmission shop check it out for you. It may not be as bad as you think. All you'd be out is the diagnostic price, but you need to question the shop to make sure they're going to do more than read codes.
i have a 96 dodge ram 1500 5.9l and i love it. however everytime i take my foot off the gas the rpms drop dramatically and sometimes the truck will even cut out on me. i replaced the idle air control valve and the throttle position sensor and it still does it. could that be the speed sensor?
Normally, Anon, when the speed sensor causes a stall, it also sets the code I listed in this post. There are a host of things that can cause what you're experiencing. Without knowing scanner data, and some idea of the maintenance you have performed, it's impossible for me to make a guess at what's wrong. A simple thing you could try is get the tank down to about an eighth of a tank and fill it with high octane Chevron or Unocal 76 gas. If that makes a difference over the days following, you may have partially clogged fuel injectors, or you've just been using cheap gas.
thanks for the post! i just replaced the speed sensor in my 04 ram 3500 with the 5.9 ho, when i pulled the old sensor out a bunch of tranny fluid came pouring out, i had just got home so the truck wasnt cooled down...i was curious because i saw a previous post saying there shouldnt be any tranny fluid that comes out. would it be bacause the truck wasnt cooled down when i changed it?
thanks
josh
Yes, Josh, changing it before cool down can be the cause, or you had the truck on a slant when you changed it.
I have a 97 Dodge Ram 2500 4x4 with a Cummins and auto transmission. It has a high performance transmission good up to about 600hp (truck has maybe 300hp), and lately it's been acting a little strange. I pull up to a stop light, and the truck acts like it's dropped out of gear. It no longer pulls away at idle if you take the foot off the throttle. But if you just about floor it the truck will get moving and after 50 feet or so it acts normally. I can drive the truck hard and it doesn't have any issues. I feel no slipping while underway, towing or climbing steep hills. Ideas? Thanks!
Lester, I'd need more diagnostic data to give you an intelligent guess. You may have a major problem with the trans front pump sealing or the governor transducer, but without a detailed scan and pressure port checks, you're flying in the dark. You need to have it checked out at a reputable shop.
I have a 2000 dakota and have mistakenly put 3 quarts of atf3 in it over the course of the past 9 months. recently it has not wanted to shift out of first gear but once it does the trans works fine till I shut the engine off. sometimes it will go for miles before its first shift. after discovering I should had used atf 4 I imediatly dropped the pan and changed out the four quarts drained and it started shifting again for about 50 miles and started again, drained the pan and it shifts again, but I am getting a output sensor code. what is the connection here with fresh fluid and the shifts if the sensor is involved also?
I doubt the ATF3 and 4 mix-up has anything to do with it, Vincent. Go ahead and replace the speed sensor with an OEM sensor and see if your shifting improves. If it doesn't, you'll need to take it in for a more thorough diagnostic at a trans shop to test port pressures and more in depth scanner data. It may be a governor pressure transducer causing the shift problem or something more serious you won't be able to detect on your own.
For checking a transmission like you have the way to tell if the problem is in the trans or the wiring is to put a pressure gauge on the governor port and start the motor. You then pull the case connector and put the trans in drive. You should see main line pressure and the trans should go into 3rd gear. If you see no pressure then you know that the problem is in the unit and the transmission needs replaced. If you have pressure and the trans goes to 3rd gear then you have to look at the wiring and governor valves.
thank you for the advice. What is throwing me off is the cosistancy of adding fresh fluid or changing it bringing back the shifting. I dropped the pan and changed the fluid again just before the last entry and vavoom ! its shifting again. haha If/when it starts not shifting out of first my first step will be to change the sensor, and if that dont work I will take it to a trans shop, the process you mentioned is beyond my capabilities so far as a facility and equiptment to do so. thank you again !
Own a 97 dodge caravan. Had the tranny rebuilt 3 weeks ago. Eveything was fine up until yesterday when the transmission started to make a whining noise, started to slip. The fluid level was very high past the top mark as well as being very hot. Have 8 codes such as gear 1-3 incorrect ratio, transaxle malfunction, overdrive hydraulic pressure switch circuit, 24 pressure switch check malfunction, P1698. Tranny seems to work ok until after heating up. Solenoid or sensor?
Anon, my guess is you've had a major failure in the rebuilt transmission. Although the P1698 points toward a possible TCM or PCM problem, the slipping, too high fluid, and overheating point toward mechanical failure such as a front pump seal failure. Take it back to the rebuilder.
thank you mr bernard for your help i replaced my speed senser 98 dodge 3500 4x4 tran shifts all gears thank you albert.diesel
I'm glad you were able to fix it, Albert. Thanks for the update.
I've located the transmission O/P speed sensor on my 1999 Dodge Ram 2500 Laramie. however not sure if i unscrew the sensor itself or disconnect the wiring? Also, is there a tab to disconnect the wire side from the sensor? Thanx!
Anon, just from your questions, it would seem like you should pay a shop to replace your sensor. If you decide to replace it yourself, then yes, you must use the tab to release the wiring connector before you unscrew the sensor.
2002 Dodge 25oo cummins auto trans goes from 1 to 3 before it slides into overdrive, no 2nd. Accidently put turned the overdrive off while I was doing about 75 and lost it. Someone told me that it was only a sensor but being a novice.....
I doubt it's any sensor, Anon. You may have a Transducer or Governor Pressure Solenoid problem, but you would need to have the tests performed as I've outlined in the original post above under NOTE - because you could also have a blown transmission.
This is Anon from 8/13/2012. I know my question sounded really amaturish but i made out Ok and saved myself a hundred bucks replacing the O/p shaft speed sensor myself. Engine light is out and code has been erased. Truck runnin fine! Thanx for the feedback Bernard! U R appreciated!
Thanks for the update, Anon 8/13. I'm glad it worked out for you.
Hi there Bernard. Have a '97 Dodge Ram B3500 with 5.2L. The cruise control is sometimes intermittent around 95 - 105 Km per hour. Not always a problem but annoying, seems to be only on hot days. No other symptons, hoses appear to be good. Could this be related to the speed sensor, or some other sensor? Thanks
Without scanner data, I can't give you anything as far as the speed sensor. My guess would be a corroded or malfunctioning Servo on your cruise control. It's the one that a vacuum hose goes to near the battery. That is a guess.
OK thanks, will check that. Martin
i just replace my output speed sensor 99 dakota 4x4 v6 3.9L...i was told that not much trans fluid would come out but about 3 qts did,,,is this normal...nut replaced fluid yet...thanks
That is not a usual fluid loss, unless you were on a slope with the front end up. If the vehicle is level, very little fluid comes out, Anon.
Bernard,
I have a 98 dodge ram 1500 5.9. ABS and Brake light stay on at times, but not every time. Usually only if have driven and shut off and restart. Never on first start of the day. I replaced the rear sensor but did not resolve. Tried to get codes, but was told they were "general". Mechanic thought it was a sticky relay in control module, but had someone else tell me I should replace the output speed sensor. Could this be the issue? Everything seems to work fine. If I replace, it looks like I can just unscrew it and it clears the plate it sits above (if I am right on the sensor location), will I lose transmission fluid? I appreciate any insight.
Thanks!
I don't know what you mean by 'general' codes, Anon. Either there are codes being set or there are not. If those lights are coming on, some code is being set. If it is setting the PO720 code, then it's possible the speed sensor on the transmission is causing your problem. If the vehicle is on a level surface, very little fluid comes out, but put a pan under it if you plan on parts changing. Make sure you get an OEM sensor from the dealer if you do.
Without more data, such as all codes from the ABS and ECM systems, or other symptoms, I can't give you anymore idea as to cause.
Hello as a woman working on my
Dodge durrango. I want to thank you!! I had done everything to my transmission but change that output sensor. I knew the code 0720 and told the dealer but they gave me the sensor for the rear instead of on tranny. I went today and got the right 20.00 piece and my tranny is now perfect!!! It was stuck in first gear and now like new. Thanks again.
I'm glad it worked out for you, Anon. Thanks for putting the update here.
Hi Bernard, sounds like I'am having the same type of problem, mine will not shift out of 1st,"2004 ram 2500 diesel" so I removed the diesel transmission fuze and it will now let me shift manually 1st to 2sc to 3rd, I know you would be guessing at this point, but would you start by replacing the transmission output speed sensor? Thanks Jim
No, Jim, I would start out by doing the test mentioned in my note I added in my main post. I suspect one of three things with yours: the trans is worn out, the filter is plugged, or the govenor pressure sensor and transducer is acting up. Those are just guesses, because without scanner data or doing the pressure check outlined in my post at the bottom, you'll be parts changing. You can try the OP Speed Sensor if you'd like. It's not that expensive, but you would be better off having it diagnosed at a shop.
i have a 2001 dodge ram 1500 2wd and my check ebgine light is on. error code is reading p1740 which could be my torque converter or overdrive solenoid. the truck drive great but sometimes i dont have 1st gear unless i do it manually. i tried ordering the overdrive solenoid from autozone and the only thing they have for overdrive is a overdrive switch. can you help me on this?
Victor, you should have the pressure checks outlined in the post above at the bottom done to confirm the problem. If you're going to parts change, then please get the part from the dealer. They will be the only ones that can supply a reliable one for what you want to do anyway. They will need your VIN number to get you the right part, whichever one you decide to parts change.
Hi Benard, I hope you can help, heres my issue. I have a 1995 Dodge Ram with the 318. It belonged to my nephew and he was several hours away and ask me to come get him and bring a trailer that his transmission had gone out. I did and parked the truck at my house where it had sat for about 1 1/2 years. He finaly told me I could have it that he wasn't going to fix it so I put on a new battery and it ran fine for about a day. Then it started acting up like the transmission was going out but I'm not sure thats it. It will crank and idle fine shifts into gears fine but if I go down the road it will start to lunge at about 10-20 MPH and about 30 is tops. It revs up like im going 100MPH but still about 30 is tops (on level ground) it will slow down going up hill. It lunges in drive or reverse. I have been told torqe converter by some but others said if it was fine for a day than that wouldn't be it and i would be able to hear it while it was ideling. Any ideas?
Re-read my original post, Anon. You need to get the codes if any, and have a shop do the testing I listed under the note in my post. That's the only way you'll know what your next step is. It could be a myriad of things such as front pump seal internal leak, governor solenoid, plugged filter, or just a worn transmission. It's impossible to pinpoint without testing.
Hi Benard, great blog by the way. I have a 2001 Ram 1500 4x4 that will not shift out of first easily, rpm's go very high. It has been doing this for almost a year now. I took it to a shop and they put a scanner on it and said it didn't tell them anything but after driving it said "it's a Dodge you need a new tranny". I don't like that. After reading a lot online I went out and did some troubleshooting. I found the sensor on the rear diff is shorted open. The sensor on the trans is not shorted and the one on the transfer case seems fine as well. Could the rear diff sensor be my fix? I am fearing that it might be the governor pressure transducer that you have mentioned a few times. I am probably just going to start changing sensors one at a time until I get to the governor pressure transducer because I will take that somewhere to get done. Any advice?
Joshua, the revving without moving usually means a failure, but I agree with you about changing a sensor that is obviously bad. When you arrive at the point about trying the transducer, try getting the tests done I list under the Note part of the original post. Here it is again:
NOTE: Here's a quick diagnostic check for major problems or governor transducer and wiring faults. I won't explain where any of the ports are because each person attempting this check should have the proper equipment, safety cautions, and manuals:
For checking a transmission similar to the one mentioned in the above post to tell if the problem is in the transmission or the wiring is to put a pressure gauge on the governor port and start the motor. You then pull the case connector and put the transmission in drive. You should see main line pressure and the transmission should go into 3rd gear. If you see no pressure then you know that the problem is in the unit and the transmission needs replaced. If you have pressure and the transmission goes to 3rd gear then you have to look at the wiring and governor valves.
I have a 2004 Intrepid here are the problems I am having with this car ...I put my key in to start it I get nothing everything turns on but the engine does not turn over so I turn it off and try it again and most times it will start on the second or third try and also I will put my car in gear to drive and sometimes when I am driving up to 60 it will start to stay on the 3 RPM and most time when I turn the car off it will go into normal gear what is causing all this grief with the car ?
Impossible for me to come up with much with no diagnostic data, Anon. My guess with the no start, but all the lights and power normal would be a security system problem. The driving problem I can't even guess at without at least a code indication. Make sure your power and ground leads are secure and your battery in top notch shape. You may have corrosion build up on the battery caused by its location. Disruptions in power or ground connections can cause memory loss in the body control computer running your security system, and unusual engine malfunctions.
You just saved me a trip. Thanks!
Hey there bernard i have a 1994 dodge ram 2500 12 valve cummins automatic trans 4x4. initionaly the darn thing would not leave the gate unless you floored it and then it would take off. once the vehicle was hot she would take off and shift properly. a local shop diagnosed it to be faulty or degrade seals so i purchase a known good used transmision and had it instaled. unit looked good with aftermarket torqe convertor and new pump. valve body was clean and pan was empty of debris. my new problem is this. truck shifts into gear starts off and then seams to slip out of gear if i ease up on the throttel she takes off again normaly. no check light yet but i have not driven it far. any ideas? i forgot to mention the new filter and fluid atf+4
I'm sorry, Seand, but without diagnostic and oil pressure data as mentioned in my original post I would have no way of knowing how you should proceed besides taking your truck into a professional transmission shop to have it checked.
Hi bernard,
I have a ram 2500 2005. I wS driving and the truck felt like it just went into neutral and slowly rolled to a stop. The truck will not move. It shifts into all the gears but just revs and will roll if pushed. When in park it does stay in park. You have any ideas whats going on?????
Thanks
MIKE
Hi bernard,
I have a ram 2500 2005. I wS driving and the truck felt like it just went into neutral and slowly rolled to a stop. The truck will not move. It shifts into all the gears but just revs and will roll if pushed. When in park it does stay in park. You have any ideas whats going on?????
Thanks
MIKE
You may have had a governor pressure transducer or solenoid failure - or a trans failure period. If you're going to guess rather than have it checked out then you can gamble and replace the governor pressure sensor and solenoid if you have a factory manual. A shop would do a pressure check as outlined in the original post towards the bottom.
'For checking a transmission similar to the one mentioned in the above post to tell if the problem is in the transmission or the wiring is to put a pressure gauge on the governor port and start the motor. You then pull the case connector and put the transmission in drive. You should see main line pressure and the transmission should go into 3rd gear. If you see no pressure then you know that the problem is in the unit and the transmission needs replaced. If you have pressure and the transmission goes to 3rd gear then you have to look at the wiring and governor valves.'
Hi BERNARD Really need some help .I have read through here and cant find the same problem im having....when i put my truck in gear sometimes it clanks and the truck jerks and when i stop say at a light it stops and then it feels like someone rear ended me and sometimes it causes the truck to die but starts right back up.so yesterday i replaced the ypi snd trsns filter there was a small pile of fine shavings but not too much.this did not fix the problem.i have no codes on my truck snd no gauge problems no problems driving either runs and shifts fine...its a 95 ram 1500 utomatic 5.9 4x4 please help thank you
I can't help you, Robert. Your vehicle needs a hands on diagnostic check. If the torque converter clutch stays engaged while stopping, it will stall out the vehicle. Why it stays engaged or something broken on the inside can't be solved on the Internet.
I have a 1998 dodge 1500 automatic I put trans in and now the od off light is on and so is trans temp won't shift to od trans not hot new cooler need ideas email ( redheadedchevyman@yahoo.com
Thomas, as with Robert in the comments above, I can't help you. You need a real diagnostic check, including pressure readings to determine what's wrong. If you've put in a used transmission, or one that is not an exact match for your vehicle, that could be your explanation.
BernardL. i have a 2005 dodge dakota 3.7 v6 and i need replace the input speed sensor but i dont know where is located.
BernardL. i have a 2005 dodge dakota 3.7 v6 and i need replace the input speed sensor but i dont know where is located.
Hi bernard,i know this posting was for a different code, but I need help and was hoping for a minute of your time.i have a 1998 dodge 1500 4x4 5.9L.my abs light and brake light on the dash are on.i ran the code and it came as po740.i replaced the overdrive/tcc sensor,filter and made no difference.my overdrive switch on the shift lever does nothing whe you press it.it is kind of gutless too and it takes all you got to get it to 45 and 2000 rpm.any suggestions will be greatly appreciated,thanks ABE
Sorry, Jaime, I can’t help you with that. You need to either get a factory manual or go to the dealer and ask to see their location schematic when you buy the sensor.
Abe, your next step is to do the governor pressure test I have at the bottom of my post under Note. Have it done by a professional. That test will determine if you’re having governor pressure problems or the trans is shot.
Bernard,
I have a 2001 Dodge 1500 w/5.2L.
My problem is on take off the transmission does not shift until thr RPM's are much higher than they should be. Except for when I try to pass it seems to shift just fine. When I step on the gas to pass it jumps all the way to first and over revs until I let of the gas. Is this a faulty output speed sensor?
Impossible to say without scan data, Bill. It seems more like a governor pressure solenoid problem. You need to take it in to be scanned first, and then depending on the results, have the governor pressure checked as in the NOTE on my original post outlines.
hi my 2000 dodge ram 1500 3.9L is going crazy it will jerk a lot when it gets to 50mph and i can mash the pedal to the floor and it almost does nothing for at least 10 seconds and then suddenly the truck will get to 4500 rpms from 2500 some times it will run and drive like normal but most of the time it does as i stated aboe it gave me the PO720 code so im gona try to replace the output speed sensor also my truck randomly wouldnt start and when ever i mashed my brakes the dash lights would come on like i turned the headlights on when i let off the breaks the dash lights go off i put the trans into nutral and let it roll back some then it crunk right up
oh and it lakes about 5 to 10 seconds to start the truck idk why it does that either its like delayed but it doesnt make a difference if i pump the gas hold it to the floor or weather its hot or cold it always starts like that
Do the obvious, and make sure you correct the PO 720 code first. Then rescan it if you still have problems, Daniel.
After I get that cleared you think you can help me out with the other problems? I really love my truck and I want to keep it as long as possible but right now it seems like its slowly crapping the bed lol I never had this many problems with my old 318 1500
There is a limit to what I can do on the Internet, Daniel. I can give you a few ideas if it sets another code, but your truck may require hands on testing for fuel pressure, trans pressure tests as in the original post note at the bottom, or an exhaust back-pressure test.
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