Hello, I just took a trip form NC to PA this past weekend. The truck ran great. The cruise control does not work though. The wipers took 30 seconds one time to turn on after i switched them on which makes me believe that both problems are releated since then are on the same lever (turn signal lever). Do the electronic cruise control boxes tend to go bad on these 6.2's?





Eric

http://www.rathwellhardware.com/TroubleServos.asp


If it doesn't work at all there are several components that could be the problem. (Turn signal lever, servo, module, speed buffer, brake switch etc)


The wipers are actually a completely different switch and the turn signal lever itself only mecahnically turns that switch. The electronics are in a completely different location.


Check fuses first, then check the brake swtich, vacuum to the servo, also check the brake release vacumm hose at the servo to make sure it holds vacuum until the brake is pressed.


You can also check the wiring at the cruise switch. There will be 4 wires, one will be live with ignition, one will be on when the switch is on, one will flash when you release the set button and the other will flash when you press resume.


Kentmore makes a tester that plugs in and diagnoses everything except the module. If you can get your hands on one of these it makes things much easier. Most GM shops should have one but you might have to blow the dust off of them. Most of the new mechanics there probably wouldn't have a clue about it. GM has completely changed their cruise control systems since then.





I just realised that this is probably for your 1991 6.2L. Is this correct? If so a lot of the information above is not relevant and I will get you the proper info.Edited by: Max Power

The 91 6.2L uses a different cruise system.


Check the switch as stated above.


Check the brake switch as well.


If it is neither of these it is most likely the stepper motor under the hood that is the problem. It is located on the drivers side firewall above the brake booster and is held on by 3 bolts.


The same tester I spoke of earlier also tests this system but an adapter is required.

Thanks for the info Max power and yes, it is for my 91 silverado 6.2.





Eric

Let me know if you have any questions. I know these systems inside and out.