Need help !!!!!!

denali13 · November 22, 2019

2002 GMC Sierra 1500 Denali/2 codes=CO237 &CO277

Left Front Wheel Speed Sensor Erratic/Rear Wheel Speed Sensor

Replaced both Front Wheel Bearing Hub Assembly

Replaced Rear Rotors and Pads

At 35 to 40 mph ABS Light And Emergency Light comes on and rough feeling under front end

Going faster you can see the Speed Odometer hand resist against the Speed

Where to go from here ????

davester · November 22, 2019

You sure CO277 is a left front WSS? Googling for that says it's a problem with the Brake Pedal Position Sensor...

check connectors and wiring?

tbarn · November 22, 2019

P0237

#PIT3521G: ABS Light On DTC C0055 C0235 C0236 Or C0237 Stored In The EBCM - keywords brake lamp - (Apr 6, 2010)

Subject:	ABS Light On DTC C0055 C0235 C0236 or C0237 Stored In The EBCM
Models:	1998-2010 All Chevrolet, GMC, Buick and Oldsmobile Mid-Sized Trucks and Utilities
	1998-2010 All Chevrolet, GMC and Cadillac Full Sized Trucks, Utilities, and Vans
	1998-2005 Chevrolet Astro
	1998-2005 GMC Safari
	2003-2009 Hummer H2

This PI was superseded to update model years. Please discard PIT3521F.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:: ABS light on speedometer may be erratic. DTC C0055 C0235 C0236 or C0237 stored in the EBCM. This concern may be intermittent and not easily reproduced.

Recommendation/Instructions:

Using the Tech 2, check the ECM/ PCM and/or TCM for any speed sensor or communication related DTCs. These DTCs will need to be diagnosed first. Follow published diagnostics for related DTCs and evaluate the vehicle after repairs are complete. If no DTCs exist in any other module, inspect the rear VSS sensor circuit(s) from the rear VSS sensor to the related module (ECM, PCM or TCM) for integrity. These circuits are 821 and 822 or 400 and 401 depending on model and model year (use SI to locate the schematic that applies to your application). Repair or restring these two circuits as needed. Evaluate the vehicle.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.