So ive got the three light issue. Codes pointed to the LR speed sensor so I replaced that. It worked with the key on acc but when I started the car all 3 lights came back on. Now its constant again. Sometimes they go out randomly then ckme back on. Im at a loss. Wireing looked fine.

 

Do you replace the whole wheel bearing assembly? Our montes are notorious for them going bad thats your wheel Speed sensor. You won't be able to tell by how wiring looks

 

The harness' are know to be intermittent as well as the wheel speed sponsors (part of the Hubble assembly) so if you replaced the Hudd then could be the harness.

 

If anything take it to dealership or brake shop that has a machine that will read abs they can tell if harness is bad

 

by three lights you mean trac brake and abs right? mines come on too but the brake will randomly come on...just another one of my items on my to do list

 

I would start by having the ABS system re-scanned for codes. See if it's the same code or different.

 

C1248
Dynamic rear proportion disabled

C1254
Abnormal shutdown detected

C1298
Powertrain control module class 2 serial data link malfunction

U1040
Loss of ebcm/ebtcm communication

Speed sensor codes are gone

 

Check you PCM harness!

 

I agree jc somthing has to be screwed up. Computers dont just break. Connections look good and fuses are fine. This might just be beyond my ability as a novice mechanic.

 

Computers can go bad... And harnesses are known for going.... And yes it may look fine doesn't mean it always is.... Take it to dealership or somewhere that reads abs and they will tell you. If it said left speed sensor and you didn't replace the wheel bearing that's the problem. Just cuz it looks fine don't mean it is