Cruise control not working

Tiny
COLTON THOMAS
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • 4.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 219,592 MILES
I have the truck listed above 1500 4.3l lu3 v6 and the cruise control has not worked ever since I got it. The guy before me had a trailer brake booster and took it out. I have looked at all the wires to make sure that they are still in one piece. I've changed the fuses and relays and cruise control is still not working. I've gone to Google but it's not helping me at all.
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Tuesday, November 5th, 2019 AT 1:58 AM

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Tiny
STEVE W.
  • EXPERT
The previous owner may have tapped into the brake switch wiring on the wrong wire and it broke when removed, happens if they used the scotch loc type connectors. I would first test the fuses in the cruise to be sure they have power. For those connect a test light to a good ground and with the key on, check for battery voltage on the top points of the cruise fuse and the brake fuse in the fuse panel in the dash. Next go to the brake switch and find the Brown wire, with the key on there should be voltage on it. Then check the Purple wire for power, be sure the pedal is fully up.

If you have power at both of those the next thing would be to find the cruise module on the drivers side firewall under the hood. Unplug it and check the connector for corrosion or damaged pins, somewhat common for that and then for battery voltage on the Light Blue wire (G) while the brake pedal is pressed and the brake lights are on.
Then with the key on but pedal not pressed check for battery voltage on the Brown wire (F) and the Brown wire with white stripe (D)
If they all test OK then the next step would be to check that the ground is good, it is the Black wire with a White stripe (E), put the test light onto a battery feed and see if the ground makes it light.
If those all check out the cruise module is getting power and ground.
The next testing will test the cruise switch functions. Now connect the test light to a ground. Go to the plug on the module again and have someone move the switch as you test. Do each test and while doing them move the turn signal stalk into both left and right positions, just in case there is a broken wire.
Testing - First turn the cruise switch to on, Test for battery power on the Gray (may have a white stripe) wire (A). Now with that switch on have them select and hold the set button. Check for voltage on the Dark Blue wire (B) and lastly, do the same with the resume button, this time looking for voltage on the Gray wire with Black stripe. If they all test good the switch isn't the problem.
Next you need to know if the VSS is okay, if the speedometer is working that signal is good.

The last test requires a scan tool that can access the cruise control module. That is because you need to see if it is responding to the various signals. I'm betting that you have already found a bad power, ground or switch by this point so you may not need the scan tool. That would be a good thing.

If you haven't used a test light to test fuses or even to test voltages this may help. Any of the cheap incandescent units will work for this testing.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester
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Tuesday, November 5th, 2019 AT 3:03 AM

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