My 2000 vert has been throwing ABS/Traction control/Active handling warnings for the past month and seems to be becoming more frequent. The odd time I will get a reduced engine power warning. If I turn off the ignition and restart 95% of the time the warnings will have cleared. I went into the DIC and cleared all the codes, drove it and retrieved the following codes:

P1125H
P1276H
C1243H
C1278H
U1255H
U1160H C
U1300H
U1255H
U1096H
U1064H
U1016H

Any help will be appreciated.

 

If you use the 'search' feature and search for 'code list' or something of that nature you will find what all your codes represent. Also do a search for 'ground points'. C5's are notorious for corroded grounds and many times you will get codes that would suggest bad components such as a PCM, TCS, BCM. When in fact it is just a bad ground. I've cleaned all my grounds and have ridded a code for a TCS module.

 

Service ABS/Service Traction Control DTC C1243 H
When the car is started the system turns the ABS pump on and off and if the voltage readout is not high enough, code C 1243 is set and you get the messages. If you do not have the interface connector for the EBCM, pull the module away from the pump section. I measured the resistance of the pump motor from pin number 8 ((from left to right) (it is the first pin on the right hand connector) to the frame ground and it was in spec according to the manual. When a pump is new or has been rebuilt it requires some break in period. If a pump has not been used for some time it will also draw more current due to sediment build up and not being exercised. With this in mind I pushed a wire into pin 8 and ran it over close to the positive post of the battery so I could exercise the pump manually. The pump came on the first time I touched the positive post but sounded sluggish. I exercised the pump about 6 more times for about 15 to 20 seconds at a time. I put the EBCM back on the pump section cleared the codes. If you try this use a heavy gauge wire and be aware the wire may get warm as you touch the battery. The pumps on these ABS units are most likely not broken in since they hardly run during the life of the car.

Clean ALL grounds ....then erase/reset all codes..to see if they come back after performing above procedure & cleaning grounds

 

Thanks guys. I have seen other threads about the grounds-will do that first and go from there. I assumed it shouldn't be a primary problem with those components when the warnings don't always come on.

 

Squigly, I have a 2000, which occasionally does some of the same things.

The P codes are accelerator pedal position.
The TAC module controls the throttle, and has a redundant system for safety. The codes you see indicate some of the redundant sensors are not agreeing. That will set the "reduced power" mode.
The TAC module is, I believe, located in a really bad place - under the battery, bolted to the PCM, behind the right inner fender panel.
As you probably know, many 2000 models (mine included) suffered leaky batteries, which dripped acid down on the computers and the vacuum lines, causing all sorts of issues. First thing should be to pull the battery and the holder, and check the computers underneath for any contammination or evidence of earlier acid leaks. The TAC module will be the smaller computer. Unplug the connectors and make sure all is okay (battery unhooked of course). Do a search on this and see if there is a ciommon failure mode.

The U codes are all serial data bus communication issues, which happen from time to time on even a very clean system. But, as stated above, do a search for ground pin cleaning, and check out those grounds, especially the frame ground behind the left headlight.
Who knows, that could be the TAC problem above also.

The C1243 is the Bad Boy. This is the one setting your ABS message.
As stated above, it's due to high resistance in the ABS motor.
Again, do a search for Code 1243, and you'l see several posts (some by me) on cleaning the motor ground wire (easy) and "exercising" the ABS motor (difficult on a 2000 model, easy on later and earlier models). The motor costs a fortune, and the excercising is a temporary band-aid. As luck would have it, my ABs message came back on again yesterday, last "excercise" was about 6 months ago.

Hope this helps.

DG

 

Thanks DG, I'm out of town away from my tools but will starting checking when I get home. All really good info.