1999 Silverado 4x4 9-codes total

[TonyaD]

1999 Silverado 5.3L 4-wheel drive. These are the concerns the ABS light & break light is on as well as services 4-wheel drive.
I have changed the switch on dash for 4-wheel drive no help.
I have check sensors on tranfer case they look good.
I have check wire around tranfer case no breaks.
I have cleaned the ground connection under frame to ABS pump and tranfer case and ground under bumper.
Changed all fuse and check to make sure they were good.

The ABS pump comes on at start and turns back off.
I have check the dash for current, and is good.
The code are
CO265
CO252
CO251
CO246
CO245
CO242
CO241
CO226
CO222
The speed sensor are reading at 3mph, when cars is not moving.
All help would be great.
Codes have been cleared these are new

[j cAT]

Originally Posted by TonyaD

1999 Silverado 5.3L 4-wheel drive. These are the concerns the ABS light & break light is on as well as services 4-wheel drive.
I have changed the switch on dash for 4-wheel drive no help.
I have check sensors on tranfer case they look good.
I have check wire around tranfer case no breaks.
I have cleaned the ground connection under frame to ABS pump and tranfer case and ground under bumper.
Changed all fuse and check to make sure they were good.

The ABS pump comes on at start and turns back off.
I have check the dash for current, and is good.
The code are
CO265
CO252
CO251
CO246
CO245
CO242
CO241
CO226
CO222
The speed sensor are reading at 3mph, when cars is not moving.
All help would be great.
Codes have been cleared these are new

this appears to be the abs control unit on the abs module under the vehicle. first check the connector/wires to it.

the internet has great info on checking this out at the module repair web sites . this is very helpful to be sure it is this unit. the relay in this unit is what usually fails.. this is very common ..


the ground on the frame rail under driver seat , must be removed/ cleaned about 80 amps flows threw this ground when the abs pump is commanded on on start up test .

[777stickman]

Originally Posted by TonyaD

The speed sensor are reading at 3mph, when cars is not moving.

Not sure what you mean by this. Is the speedo reading 3 mph? If so you may want to change out the VSS.

[TonyaD]

Originally Posted by j cAT

this appears to be the abs control unit on the abs module under the vehicle. first check the connector/wires to it.

the internet has great info on checking this out at the module repair web sites . this is very helpful to be sure it is this unit. the relay in this unit is what usually fails.. this is very common ..


the ground on the frame rail under driver seat , must be removed/ cleaned about 80 amps flows threw this ground when the abs pump is commanded on on start up test .

I was thinking the ABS module as well. I was thinking most of the codes could be ghost codes. But the ABS pump does power on at start up. If the module was bad would it power the ABS pump on at start up? I have check into rebuilding the ABS module, have you or any one had luck with rebuilding the module. If so which company does a good job? When removing the module it should just discount from top of pump? Which is under the driver sides frame. Thanks again!!!

[j cAT]

Originally Posted by TonyaD

I was thinking the ABS module as well. I was thinking most of the codes could be ghost codes. But the ABS pump does power on at start up. If the module was bad would it power the ABS pump on at start up? I have check into rebuilding the ABS module, have you or any one had luck with rebuilding the module. If so which company does a good job? When removing the module it should just discount from top of pump? Which is under the driver sides frame. Thanks again!!!

what is with this 3mph ? how are you determining this ?

the transmission speed sensor drives the odometer.

when you look up these ABS module repair sites post back with your findings. like I said they offer good troubleshooting to locate these issues.

[danielsatur]

The ABS system needs data from either the VSS, and wheel speed sensors,
I would focus on the VSS 1st, this might give you problems with transmission shifting, and lead to bad transmission.

[TonyaD]

The 3 mph came when the codes were pulled. Roppels a auto shop pulled the codes and looked at the speed sensors on the right front wheel gave a code of no signal and it also showed the sensor reading at 3 mph. The same reading on the left front wheel sensor 3 mph and no signal along with the back right wheel. The transmission shifts great, it also runs great, starts with ease.

[j cAT]

Originally Posted by TonyaD

The 3 mph came when the codes were pulled. Roppels a auto shop pulled the codes and looked at the speed sensors on the right front wheel gave a code of no signal and it also showed the sensor reading at 3 mph. The same reading on the left front wheel sensor 3 mph and no signal along with the back right wheel. The transmission shifts great, it also runs great, starts with ease.

good that this is most likely the abs module or wiring /grounds..

make sure the grounds and the other wires at around this module are good and use the troubleshooting guides at the internet module repair site[s].....