ABS light on with codes C0225 and C0221?

DANIEL KELLER

MEMBER
2001 CHEVROLET BLAZER
4.3L
6 CYL
2WD
AUTOMATIC
200,000 MILES

ABS and brake lights are on. First started with no communication to ABS module, reflowed the solder and got communication with error codes for both front wheel speed sensors open circuit. Change ABS module still has same error codes.

C0225 left front wheel speed sensor circuit open
C0221 right front wheel speed sensor circuit open

Looking for wiring diagram and connector pinout. I should have added that when I clear the codes, they come right back without driving the vehicle.

Sunday, March 23rd, 2025 AT 1:02 PM

4 Replies

KEN L

MASTER CERTIFIED MECHANIC
54,137 POSTS

Yep, that sounds like a wiring issue, but I have seen bad wheel bearings cause this issue as well. So, if the wiring is good check the bearings out, also make sure there is a reluctor wheel on the rotors as well.

This guide can help you with the testing:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the images (below). Let us know how it goes.

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Sunday, March 23rd, 2025 AT 4:48 PM

STEVE W.

MECHANIC
15,233 POSTS

That sounds like a hard fault in the system. You can test the harness at the C1 connector on the EBCM Pins A2 and B2 are the left and A3 and B3 are the right. Basically you are looking for continuity through them. If you have access to an O-Scope you can also connect it to those pins and spin the correct wheel and see a sine wave if the sensors are okay.

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