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Service transmission light on - jerking - please help!


iwanta2000caddy

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Hey guys,

It seems that ever since I have owned this car (3 months), I am seeing more and more problems.

For the past few weeks I have had not smooth idle. The idle sits quite low, and almost chokes when at a stand still. Starting up can be sometimes difficult but she always starts.

When i started my car after work today, the transmission JERKED/CLUNKED from P to D and shook the whole car. In disbelief I shifted back into P and waited a few second. I then shifted from P to D and it jerked and clunked again.

For the rest of the trip home the transmission shifted poorly (especially when coming to a stop it almost seemed to clunk). When I got to my destination the "service transmission" message came on my OBC dash.

When I got home I turned the car off, turned it back on and the transmission message is gone. Moreover, it doesn't clunk when decelerating.

Any ideas as to what is happening with it????????

FYI I put regular gas in a few days ago, ever since then the idle was *smurf*, check engine light has been on, car has a hard time starting, etc. and now the transmission is acting very poor.

THanks for the help in advance folks!

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Your car has an on board computer that you can download the diagnostic codes from. Download the codes and post them here. This sounds like a P0717 ISS Speed Sensor problem but post your codes

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

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Hello,

Here are the codes:

ABS C1287 HISTORY

NO AMP

NO DDM

DIM B1983 HISTORY

DIM U1255 HISTORY

DIM U1016 HISTORY

NO IPC

IPM B1652 HISTORY

IPM U1016 HISTORY

IRC B1245 HISTORY

IRC U1016 HISTORY

NO MSM

PCM P0340 HISTORY (i think this is a PLM or PCM and i wrote it down wrong)

PCM P0341 HISTORY (i think this is a PLM or PCM and i wrote it down wrong)

PCM P0748 HISTORY (i think this is a PLM or PCM and i wrote it down wrong)

PCM P1599 HISTORY (I think this is a PLM or PCM and i wrote it down wrong)

NO RFA

NO RIM

NO RSS

SDM B1001 HISTORY

TTM U1016 HISTORY

VTD B1009 HISTORY

VTD B2734 HISTORY

THanks for the help in advance! I don't think I am going to drive her until i find out what is wrong.

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....

PCM P0340 HISTORY (i think this is a PLM or PCM and i wrote it down wrong)

PCM P0341 HISTORY (i think this is a PLM or PCM and i wrote it down wrong)

P0340 - Camshaft Position (CMP) Sensor Circuit

P0341 - Camshaft Position (CMP) Sensor Performance

These two could be related to your idle and start situation. Camshaft position sensor failures are rare, but certainly possible. If it was my car I would clear the codes and see if they returned.

PCM P0748 HISTORY (i think this is a PLM or PCM and i wrote it down wrong)

P0748 - Pressure Control Solenoid Circuit Electrical

This is the first time I have seen this code reported. I will have to research this one.

PCM P1599 HISTORY (I think this is a PLM or PCM and i wrote it down wrong)

P1599 - Engine Stall or Near Stall Detected

This is informational only; you already know the engine was near stalling.

Nuisance faults and codes are not unusual; the OBD system is really very good, but not perfect.

If it was my car, I would clear the codes and drive it. The 'hard' shifts you mentioned are actually protecting your transmission (P0748), so don't be concerned about driving the car.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Good job JimD. One of the symptoms that the P0717 causes is hard shifting. That is because it defaults to a higher line pressure. Now I know you don't have the P0717, but you have a P0748 that has to do with the pressure control solenoid (I replaced my solenoid when I did my ISS sensor). This is undoubtedly why you are having hard shifting. Jim is correct, this is the first time we have seen this code.

Have you been through deep water recently? Check the plug for dampness either from water or tranny fluid, if it is wet at all, clean it with electrical contact cleaner.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I've seen codes caused by pressure-washing the underside of a car due to the water causing temporary short circuits. This is the season for salty puddles, too. I would put the car through a car wash that got the salt out from under the car first.

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Thank you for the fantastic and informative responses. You people really know your stuff.

The car was pressure washed a day ago or so. There was a lot of dirt on the grill, so water cold have inadvertantly gotten into the engine compartment and caused my problems.

update* I added 92 octane to the car today to see if some of the problems would go away. Check engine light has gone off, idle is returning back to normal, car is not stalling.

I will take a look at the plugs and sensors tomorrow, and take the advice to dry them with electrical cleaner

Thank you!

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Thank you for the fantastic and informative responses. You people really know your stuff.

The car was pressure washed a day ago or so. There was a lot of dirt on the grill, so water cold have inadvertantly gotten into the engine compartment and caused my problems.

update* I added 92 octane to the car today to see if some of the problems would go away. Check engine light has gone off, idle is returning back to normal, car is not stalling.

I will take a look at the plugs and sensors tomorrow, and take the advice to dry them with electrical cleaner

Thank you!

I am sorry I didn't mean plugs, you said you would take a look at the plugs. In the first photo there are two arrows, you squeeze at those arrows to open the /plug / connector. There is a main plug on the transmission, here are a few photos

TrannyConnector.gif

ISSCrossover6_07004.jpg

ISSCrossover6_07012.jpg

ISSCrossover6_07002B.jpg

Dirty

ISSCrossover6_07001B.jpg

Cleaned up

ISSCrossover6_07003B.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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update* I added 92 octane to the car today to see if some of the problems would go away. Check engine light has gone off, idle is returning back to normal, car is not stalling.

I'm glad to hear your car is running better, but it should run well on just about anything with a higher octane rating than peanut oil. Yes, I'm being a little facetious, but it SHOULD run just fine on regular fuel. You need to investigate further. Any chance there was water in your fuel?

Regards,

Warren

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  • 2 weeks later...

Hi Warren and gang,

Well I cannot seem to shake the "service engine soon light"

The weird thing is that it basically it will come on for 4 trips, and then somehow it will be off for a trip. And then back on, and so forth. For the past few days it has been on.

Some weird symptoms I have noticed when the light is on are:

*when starting the vehicle it almost seems like it cannot catch, sometimes it doesn't start first try.

*the idle is odd. It will idle at like 700RPMs, and then fall unexpectedly to like 500RPMs

*the idle will pulsate when at a standstill. It only happens when the vehicle warms up. It only pulsates 100-200 RPMs or so but it is definately noticeable and frustrating.

*loss of power.

*The less gas I have, the higher the probability that the vehicle operates like the above.

Oddities:

*sometimes I play with the gas cap, 1/10 times the light will come off

*I have tried turning the vehicle off, and pulling the oil dipstick and putting it back in. 1/20 chance says the light goes off

Anyways, the codes I listed above are still the same. I would be greatful for any further thoughts as my local cadillac dealership refuse to return my calls to have the vehicle serviced.

Thanks!

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Since your code goes away ever few days its because it's intermittent and the system resets after a 40 successful restarts according to this diagnostic chart. There are two more pages to this diagnostic if you want them, I will post them.

I wanted you to see a description of the code. As you can see, it states to check the 20 pin connector as I noted above.

If you DO have this job done, while the side cover is off, replace the ISS speed sensor, (1) sprocket thrust bearings, side cover gasket, island gasket, output shaft (axle) seal and TCC solenoid, Good Luck with this.

P0748PCSValve.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Since your code goes away ever few days its because it's intermittent and the system resets after a 40 successful restarts according to this diagnostic chart. There are two more pages to this diagnostic if you want them, I will post them.

I wanted you to see a description of the code. As you can see, it states to check the 20 pin connector as I noted above.

If you DO have this job done, while the side cover is off, replace the ISS speed sensor, (1) sprocket thrust bearings, side cover gasket, island gasket, output shaft (axle) seal and TCC solenoid, Good Luck with this.

P0748PCSValve.jpg

Hey thanks for the response.

Yikes, all those repairs sound expensive. How critical is it that the car be repaired soon? Do you think it is ok to drive with? Since the light has been going on and off I have driven it for a good 500-600 kms. And I think you are definately right about the problem, the transmission has the slightest kick to it when driving slowly and changing gears.

Update. I just put premium fuel in. The car starts quicker but the engine light persists.

I also reset the codes. Hopefully it will tell me what the hell is going on.

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P0385 - Crankshaft Position (CKP) Sensor B Circuit

That's an easy DIY fix. Most folks would recommend changing both sensors while you are doing it.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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all codes reset. Check engine light is now off.

idle is pulsating like crazy now.

Only PCM code is PCM P0385

I guess it is time to park her... shes hurtin

As Jim noted this is an easy repair and quite common in the 2000 model year, it will create stalling but it will start up immediately afterward. We can post the procedure and photos if you decide to do the crank sensors.

With regard to the tranny problem, IF you can find a mechanic or a tranny shop that will do the job, you might find that it is inexpensive compared to the dealer. The engine carriage needs to be dropped down on the drivers side (and a little bit on the passenger side), to gain clearance of the side pan and then all is accessible.

Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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all codes reset. Check engine light is now off.

idle is pulsating like crazy now.

Only PCM code is PCM P0385

I guess it is time to park her... shes hurtin

As Jim noted this is an easy repair and quite common in the 2000 model year, it will create stalling but it will start up immediately afterward. We can post the procedure and photos if you decide to do the crank sensors.

With regard to the tranny problem, IF you can find a mechanic or a tranny shop that will do the job, you might find that it is inexpensive compared to the dealer. The engine carriage needs to be dropped down on the drivers side (and a little bit on the passenger side), to gain clearance of the side pan and then all is accessible.

Mike

Hi Mike,

great response. Thank you very much for all your help

I am going to call Napa tomorrow @ 8 to find and install the crank sensors. So no problem here.

Am I harming the transmission by not having the tranny work done? I just didn't expect to have to fix so much on a newer vehicle (I already forked up $ to install a new front left strut). If you could ballpark a figure - what do you think the dealer would charge to have the tranny work done?

THanks Mike.

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oh and another thing.. After clearing all the codes the PCM 0385 is the only code now that is displayed.

It was noted above that the transmission should be serviced. Shouldn't the PCM transmission error codes show up in the history?

I drove my car over a year with the P0717 code which causes similar symptoms as you seem to be getting. My code would flash about 3 times a week, I manually erased it and I was good to go for another half of a day. My sensor was definately bad however. Personally, I think you would be OK, to drive UNLESS you feel ANY slipping, if it SLIPS park it immediately. IF its just rough shifting because it has defaulted to a default line pressure, thats ok. Just don't drive it hard.

Your code is intermittant. I would think that it would end up in history, Ill look in the manual to see what else it states about it.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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OK folks, thanks for all the help

I replaced both Crankshaft sensors. Many people on this board said that it was an easy job, I would urge those that are non-mechanically inclined to have a mechanic fix them. In order to reach the top sensor, I had to loosen the frame cradle bolts and move the engine support out of the way. If you do this.. please

SUPPORT THE ENGINE!

Anyways the P0385 code went away, but all my problems persisted (check engine light, weird pulsing idle at standstill in drive). I got pissed off - brought it to Cadillac to fix. Turns out it was the camshaft sensor (P0340, P0341). $330.00 incl parts and labour

Hopefully this thread will help others diagnose their cars when they have similar problems

Thanks for all your help,

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That was not necessary, all you needed to do was remove an inspection cover from the bottom and remove the oil filter adapter and you are right there.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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That was not necessary, all you needed to do was remove an inspection cover from the bottom and remove the oil filter adapter and you are right there.

I see what you are saying. I just didn't want to risk breaking any of the oil gaskets or whatnot.. i recently had the car in for a oil filter change etc.

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That was not necessary, all you needed to do was remove an inspection cover from the bottom and remove the oil filter adapter and you are right there.

I see what you are saying. I just didn't want to risk breaking any of the oil gaskets or whatnot.. i recently had the car in for a oil filter change etc.

I understand, but store that for future reference. You would not have dropped much oil at all either. If you ever decide to remove the oil filter adapter there are 2 o-rings you should replace. I tip my hat to you, for the method you used, that was hard.

Hey, did you remove the front engine mount?, I need to replace mine, how bad was that?

OilPressureSwitch005.jpg

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Hi Mike, it wasn't actually all that bad if you know what you are doing.

Here is the process that was used. PS I am not a mechanic and this is what i observed.

- make sure the car is raised (best if you can actually walk under the vehicle).

- make sure the engine is supported with something (whether it be by hoist or whatnot)

- unscrew about 5-8 bolts (brake cables, the engine mount nut, the two bolts that hold the engine mount in place to the engine, unscrew both cradle bolts and a few other bolts that I cannot remember).

- You should be able to wiggle the engine mount out of place, and find a way to squeeze it by the other parts (it is an awkward looking piece as it has a 5 inch screw sticking out of the bottom of it - you will need to find a way to wiggle it out - once loose i aimed it diagonally and finessed it out). I had the cradlebolts unscrewed slowly, while checking to see if the mount would come out of place. If not, I would continue to loosen the cradlebolts and pulled down on the frame slightly to navigate the engine mount out. Please note that when I did this I only moved it to the lefthand side so there was room to get to the crankshaft sensors.

- i guess replace and then you are done.

I would say at most you would be looking at a 45 minute job from start to finish.

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Hmmm, I didn't plan to drop the carriage to replace the front mount. I think a member did it by supporting the engine, removing the bolts and squeezing it out once the cooling fans are removed. Personally I wouldn't mind removing the radiator if I had to. I need to replace that mount I am getting a lot of vibration. Its getting warm so the day is coming

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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