Cruise control issues.

[celticwarlock]

I have an '01 SC2 with cruise control which does not work. The switch on the steering wheel apparently works, the "wrench light" in the dash cluster is not illuminated when the car is running (which I am told means that the module is working), and I replaced the TPS. I also verified that the cruise control module is actually connected to the throttle.
Any ideas would be most appreciated.

[OldNuc]

Are any of the dash indicator lights out?

[lamping.ap]

Is the airbag light on? Does the horn work?

[OldNuc]

The wheel ground is good if the pod LED lights up other than the ground there is noting common between cruise and the horn.

[lamping.ap]

True. Dumb question. If the OP has a good scantool he can check the signal to the PCM.

•Check for any cruise control, cruise/brake, transaxle range switch, PCM internal fault, output speed sensor or TP sensor DTCs. Diagnose those first as they are probably the cause of an inoperative cruise control system.
•Verify power and ground circuit integrity at the cruise control module.
•Verify that the PCM can recognize the CRUISE SWITCH On/Off, the CRUISE SET/COAST and the CRUISE RES/ACCEL switch transitions by cycling switches and monitoring the parameters on the scan tool.
Important: The cruise switch must be On to read the SET/COAST or the RES/ACCEL switch inputs.
•Verify the PCM can recognize the cruise/brake input by depressing the brake pedal. This can be read as BRAKE SWITCH on the scan tool.
•Verify ignition voltage is present at the cruise control module on circuit 86 (cruise/brake input) when the brake pedal is released.

[OldNuc]

The scanner that will do that for a Saturn is in the 600+ range. If the OP has such a scanner he would not be here asking this question.

[lamping.ap]

Originally Posted by OldNuc

The scanner that will do that for a Saturn is in the 600+ range. If the OP has such a scanner he would not be here asking this question.

I have a bluetooth scanner w/ Scan XL. Not nearly that expensive. It can read if the cruise is active, cruise set speed, cruise delta, and the brake switch; among many other things. But if he doesn't have access to such a tool, troubleshooting is more difficult.

[OldNuc]

The cruise is probably not active because the brake switch enable 12v is missing due to a failed brake switch enable signal. Every other failure will eventually set the service light. The brake switch signal also goes to the ECU and TCU so the open would be right at the module or there would be other symptoms.

[OldNuc]

That Scan XL looks to be about a 320.00 package.

[lamping.ap]

According to the schematic, cruise 2 fuse powers the steering wheel controls. The light at the steering wheel is turns on. So, cruise 2 fuse is good. Cruise 1 fuse sends ignition voltage to the cruise control module and sends power to the brake switch. Assuming that fuse is good, the brake switch is a good place to start. The brown wires from the switch go to the PCM and the cruise module. Check the brown wire, pin 7, in the black 6-way, at the cruise module, to make sure it is getting brake input.


A little off topic but, the Scan XL software came free during a special they were running with the bluetooth module I purchased. Software alone runs 90$. Add another 90$ for the GM enhanced pkg. Prices are from http://www.scantool.net. The developer is http://www.palmerperformance.com.

[OldNuc]

There is a bit more to it than that, but it is the place to start. The module connector is rather expensive and hard to get so do not just disconnect it from the module and probe into the connector with force as it will fail, just make contact on the edge of the pin. Verify 12v at pin 5 as well although it should eventually set a code if missing.

[celticwarlock]

Sorry for the late response....I find myself on the road VERY often and I therefore cannot access the 'Net regularly. Indeed, there is nothing to indicate an obvious fault....when the key is first placed in the ignition, everything is as it should be (SES and "wrench" light on), and then they shut off when the car is started. As I mentioned, the steering wheel switch comes on and stays on when activated.
The brake light switch circuit seems like a great place to begin. Correct me if I am wrong, but are you saying that with the module connector removed, key in the ignition (& turned forward), and a probe on the #5 pin, there should be 12V? Thank you both for all the input thus far, by the way.....

[OldNuc]

Note the wire colors so you can ID the correct pin. Yes disconnect the module and then set up to measure voltage by clipping the ground lead to the frame and verifying it is a good ground by touching the positive battery terminal and reading battery voltage. Leave the ground lead alone and just touch the red positive lead to #5 and then #7 and note reading as below.

#5 - pink - is 12v when the key is in RUN but not crank.
#7 - brown - is 12v as long as the brake is not depressed and key in RUN but not crank.

Both must be present. If you happen to set a code or suspect you may have after reconnecting everything pull the PCM B fuse in the engine compartment fuse box for a couple of minutes and replace.

Be careful probing the module connector.

[celticwarlock]

Thanks, Nuc. I will get after this later in the week (weather is poor here) and post my findings. Your indispensable help is much appreciated.

[OldNuc]

There are 2 rows of pin holes in the connector. The bottom row,farthest from the red pin clip, are the actual connectors. There is a tab along the side of the top row that is part of what holds the individual connection in place, you can test against that tab as well without risking damage of the actual connector.

[celticwarlock]

Well, it only took like 10 years, but I finally had time to test this. Boy, did I get sidetracked.

There is voltage at the points in the cruise control module connector where there should be. In fact, when I press the brake, the voltage at the brown wire disappears, and promptly re-appears when the brake is let go. This means the module is getting power. There are no indicator lights in the cluster that have burnt out, and the wrench light isn't on.

Where should I look next?

[Ricketts]

10 years is a long time. OldNuc has since passed away. A wealth of knowledge gone.

Did the cruise work for you at some point in the past, or did you buy the car used, with non-functioning cruise?

[celticwarlock]

Thank you for the reply.

Yes, 10 years is far too long. OldNuc is a legend for sure, but I imagine someone else here would have the answer.

No, the cruise control has never worked for as long as I've owned it (I bought it in 2010).

[billr]

I hope somebody else comes to your rescue. I am unfamiliar with this CC, but peeked at the schematic posted in reply #11. I would start by looking for activity on the GRA wire from the steering-wheel CC switch to the PCM. Pin J2-3 at the PCM, I think (schematic is blurry). Yeah, I would like it to be something simple, like the clock-spring cable.

"Is the airbag light on? Does the horn work?" Was that ever answered? Also, is this trans auto or manual?

[Ricketts]

Originally Posted by celticwarlock

No, the cruise control has never worked for as long as I've owned it (I bought it in 2010).

OK, the reason I asked is some people tried adding cruise control afterwards, with varying rates of success. The wiring harness for cruise is already there, so people would go to junkyards, pull the control box and the steering wheel switchgear from another Saturn, and simply plug it in. But the car had to be programmed to recognize the cruise control. Some people were lucky, others not. I think they needed to have someone with the "Tech 2" software (can't recall if that's the correct name) connect into the car and enable the cruise function in the car's computer, but not everyone had access to someone with the software.

Just a thought. There might be the potential someone tried to add it but ran into the programming roadblock