2004 Buick Rendezvous cruise control problems

Maintenance/Repairs
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1

I am having problems with the cruise control on my 2004 Buick Rendezvous, and specifically with the cruise control release switch. When attempting to activate cruise control, no light is displayed on the dashboard and cruise control does not work at all. Here is what I have found and what I have tried:

-I verified that all taillights and brake lights are working correctly.

-I verified that the cruise control fuse is working and the cruise control module is receiving power.

-I verified that the cruise control switch (off/on/resume/set) is working correctly, as it is sending appropriate inputs to the cruise control module.

-I verified that there are no errors in the PCM inhibiting cruise control.

-Replacing the cruise control module had no impact, so I am convinced that the problem does not lie in the cruise control module.

-I found that the cruise control release switch was bad (fails open) and replaced it (twice!), but each time cruise control worked for only 5 or 10 seconds before cutting out. After this, the (new) cruise control release switches were found to have failed.

What could be causing my cruise control release switches to immediately fail? How can I try to track down what the underlying problem is?

2

Where, exactly, is this switch that is failing?

3

Do you have the complete instructions on how to replace the cruise control release switch at the brake pedal?

Tester

4

This switch is located at the brake pedal. The main switch there is the
brake light switch (which works fine), and the cruise control release
switch is the smaller one above it.

5

I didn’t have instructions, but it just twisted a bit and came out and the
new one went in the same way–seemed easy enough. Is there something tricky
about it?

6

  1. Install the cruise control release switch electrical connector.

  2. With the electrical connector index notch at the 10 o’clock position, install the cruise control release switch to the retainer.

  3. Important: DO NOT MOVE OR PUSH THE BRAKE PEDAL.

  4. Slide the switch into the retainer until the plunger is fully depressed into the barrel.

  5. Rotate the cruise control release switch clock-wise until the travel stop has been reached. (approx 60 degrees).

  6. The connector index notch should now be at the 12 o’clock position.

Tester

7

Thanks, Tester. This is how I installed them.

8

So, no outwardly obvious clue (broken part) as to why the several switches failed?

9

Where are you getting the replacements from? Are they reputable?

Why not do a bench test of the switch first. Just measure it with your ohmmeter out of the packaging. Manually depress it numerous times and recheck. Is it still good? This could weed out mechanical failures due to defects in materials. Now install the switch but do not make electrical connection. Drive car normally, using brake pedal for a decent length trip. Use your meter to verify switch still OK. Now make electrical connection and repeat test drive. Is switch bad? If so, it is failing under load. Review schematic to see how switch is used electrically and determine if excessive current situation exists…

10

An update:

I got a new switch, carefully tested it as TwinTurbo suggested, and installed it. The result is that the switch has remained good, but the cruise control still does not work at all (no light on the dashboard and no engagement). So now I need to find another problem that’s preventing cruise control from operating, but I’m at a bit of a loss as to what else to check… Perhaps I should test some electrical circuits, but it’s hard for me to do this without a wiring diagram.

11

Here’s the Cruise Control Schematic (click for full size).

12

Thanks, Bugmenot. I’ll try to test the wiring.

13

My '05 showed an error of the brake switch TCC, torque converter clutch. It is the other switch at the brake pedal. The computer needs to see 12 volts from the switch to allow cruise to engage. The switch is normally closed until the brake pedal is depressed. The 12 volts comes from a 10 amp fuse in the center console fuse block . The switch isn’t shown on the cruise control schematic. I found the fuse missing all together. The fuse also powers the rear view mirror indicator for the passenger air bag activation display. If you don’t have any indication on the bottom of the rear view mirror, the fuse is bad or missing. When I installed a fuse, the cruise worked and I had the air bag indicator light up on the rear view mirror.

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