Hi Guys

I’m new here and picked up a 1999 C5 last week. The car came from the factory with an automatic per the RPO code on the glove box, and the “press brake when shifting” message that pops up on the DIC when the car is first started. At some point it was converted to a manual. Whoever did the work did a pretty good job as the message and RPO code are the only remnants of the auto. The car has XS Power long tube headers, and a B&B exhaust, and appears to have been tuned at some point (my BlueDriver scanner didn’t automatically pull in the VIN). The car does have higher mileage, but it’s still in great shape.

Unfortunately, the cruise control does not work. It’s not a big deal, but it would be nice to have it working. I’ve checked the 10 amp fuse in the passenger’s side footwell, have scanned the car for cruise control codes (none present), and have also looked at the brake and clutch pedal switches. Here’s where I run into a few questions a bit outside the norm. Both switches appear to be adjusted properly, but as I suspected with the auto / manual swap, there is no harness plugged into the clutch switch.

1. Would it be fair to say that the system should still operate without this switch if the car originally came with an auto and auto wiring harness (obviously I’d have to be careful about pushing the clutch in with the cruise on)?

2. Would GM have used the same wiring harness under the dash for both cars, and tucked the clutch switch harness away in a loom somewhere on the auto cars?

3. When I flip the cruise control switch to ON, nothing lights up on the dash to indicate the system is on or ready. Do these cars have a cruise light that is supposed to come on when the switch is turned on and before the cruise is actually set with the button on the end?

3. Is it possible that the tuner turned off the cruise control with his tuner due to the complications with the manual swap and no clutch switch harness?

4. Does anyone have any suggestions as to how I should proceed with troubleshooting based on my scenario?

Thanks in advance for the assistance!

 

When the system works, it puts a message up on the dic indicating cruise control set at X speed.

The tuner likely did not turn it off. If that were done it would more likely be done via a tech 2. Still not likely done.

As far as harness lines, I cannot say.

With the manual swap, all I can suggest is that it is likely not seeking input from the disconnected clutch switch. Though it may be seeking a signal or input from the electronic auto which is missing.

This would be a good mystery for the likes of Paul Koerner. He has a Fb page TheCorvetteMechanic and he is a deep trove of factory information.