Questions and Answers

Chevy S10 Won't Engage 4WD Q. Hello, I have a 1992 Chevy S10 4WD. The person I purchased the vehicle from told me that the 4WD stopped working a couple years ago. It has the dashboard button to engage the 4WD. The lights on the switch come on when pushed but doesn't engage. Any ideas as to what may be the problem? Thank You, Dale

A. If you push the 4 HI button, the encoder motor should be heard making a shift inside the transfer case. If so and front wheels don't engage, there could be a vacuum problem to the front differential. There is a switch on the transfer case that is supplied engine vacuum. When 4x4 is engaged, the switch transfers vacuum to the servo which then has a cable to engage the front axle.

Could be bad vacuum hoses to the servo or the switch itself. There may also be codes stored in the system which can be read through the switch by jumping 2 pins in the ALDL connector but I'm not sure which 2. Good luck.

Diagnostic Trouble Codes - 1992