So my cruise hasn't worked for ages and I would like to figure out what's wrong. It used to work, then worked intermittantly, then completely quit, never to work again.

Brake lights work fine. None are burned out.

I've gone through the onboard diagnostic (press off then KOEO) and push the cruise buttons. Each flashes once, indicating nothing wrong with the test.

So I've gone on to test for power at the servo.

Pin 9 shows 12V (as it should)
Pin 7 shows 12V (as it should)
Pin 5 shows 7.9V (as it should) at KOEO
Pin 5 shows 12V (as it should) when pushing the cruise ON button
Pin 5 shows 0V (as it should) when pushing the cruise OFF button
Pin 5 shows 3.5 V (as it should) when pushing the SET/ACCEL button
Pin 5 shows .9 V (don't have the spec) when pushing the COAST button

Now here is the problem.

Pin 4 shows 12V when stepping on the brake pedal (as it should)
Pin 4 shows 12V when NOT stepping on the brake pedal. (Bad! should read 0V!)

Same thing with the clutch pedal if it matters. No change.

So where does the problem lie?

The wire at pin 4 is tan/lt blue (T/LB), as as far as I can tell from the wiring diagram, it comes from the Clutch Pedal Position Switch via the Brake Pedal Position Switch. So I am guessing it has to be one or the other, right?

Apparently the speed control servo thinks that either the clutch is pushed in, or the brakes are being applied all the time. Is this a safe assumption?

 

Has the recall been done? If so, the fuse may be blown in the recall harness. If not, go get it done immediately!

I'd suspect a bad SCDS (the switch on the master cylinder that the recall harness connects to).

http://www.rockauto.com/catalog/more...666&cc=1385377

$15.82 at Rock Auto.

 

My master cylinder doesn't have that switch. The only electrical connector on it is the one on the side bottom that detects low brake fluid.

 

Mine is a 2003 4.2 manual - it doesn't have the recall harness because it had the improved switch from the factory and wasn't in the recall.

 

Yeah, like I said, my master cylinder does not have that switch.

 

I wonder if someone in the past changed the master cylinder with one that was for a vehicle that didn't have cruise control... because there is just a flat casting on the master cylinder where that switch "would go", but there is no connector there, it's just flat and solid.

I also see that there are 2 wires nearby the harness that look like they have been spliced. I bet someone removed the switch and 2 prong harness connector and bypassed it by wiring them together with connectors.

 

OK, here is an update.

I got the cruise control working again. It was the clutch pedal position switch. Took the connector off and clipped a paper clip into three u-shaped pieces that I could use for jumpers to connect 1&2, 3&4, 5&6. Once I connected 3&4, the voltage at the cruise servo (pin 4) dropped to 0V and using the brake then made 10V, and no brake pedal was 0V again. PERFECT!

So I have a new CPP switch coming from Amazon ($25) and will use a paper clip in the meantime.

Freaking awesome!