I have a 99 Blazer with the T-case 4x4 Auto option (4 button). When I put it in 4x4 auto the service 4x4 light comes on and I get a C0374 code and when I put it into 4x4 hight I get a C0305 code. I have checked all the plugs on the t-case and all look clean and OK. Where is the front propshaft speed sensor located so I can test it? I am thinking the C0305 code is the C0374 code problem.

Also if I find that it's bad, anyone have a part # so I can order online.

 

C0305 - Front Propshaft Speed Sensor System Malfunction
C0374 - General System Malfunction

The C0305 code can definitely cause the C0374 code so start there. Inspect the wiring harness to the front speed sensor for damage as this can cause a C0305 code to set. The front prop speed sensor is located near the front output shaft on the top of the transfer case.

 

Thanks,

Just what I needed. I will get it up on the lift in the morning and check everything out.

Charles

 

CETthomas,
Any updates to the issue you were having?

 

Yes, it was the sensor. With the help form swartlkk I found the problem and had it fixed in about 30 min.