Foxbody Mustang Cruise Control information, location, wiring diagrams
- Thread starter Mustang5L5
- Start date
Finally got around to using the Rotunda 007-00013 speed control test unit.
Pretty straightforward. Step #1 is to become a contortionist and reach up under the dash to disconnect the cruise amplifier wiring.
I ended up using a thin screwdriver to gently pry the retaining latch out, while pulling downward.
You can see the yellow cruise module here and the unplugged connectors.
Plug them into the rotunda module
The test is designed to run with the engine running. I didn’t want to do this so I used a vacuum pump. I hooked the vac pump up to the vac tree and that gave the servo enough vacuum to run through the tests. I ran the test with key on. Everything functioned well and it was cool to watch the throttle pedal activate on its own due to the vacuum servo.
One thing that did hang me up. Taillight LEDs. They don’t create enough resistance to properly activate the tester and signal a good circuit. I could only get it to test good one time out of 20-30 tries. I replaced one led with a standard bulb
And that did the trick. May need to add a resistor to the circuit.
Close up of the test unit. I made a video in the next post
Pretty straightforward. Step #1 is to become a contortionist and reach up under the dash to disconnect the cruise amplifier wiring.
I ended up using a thin screwdriver to gently pry the retaining latch out, while pulling downward.
You can see the yellow cruise module here and the unplugged connectors.
Plug them into the rotunda module
The test is designed to run with the engine running. I didn’t want to do this so I used a vacuum pump. I hooked the vac pump up to the vac tree and that gave the servo enough vacuum to run through the tests. I ran the test with key on. Everything functioned well and it was cool to watch the throttle pedal activate on its own due to the vacuum servo.
One thing that did hang me up. Taillight LEDs. They don’t create enough resistance to properly activate the tester and signal a good circuit. I could only get it to test good one time out of 20-30 tries. I replaced one led with a standard bulb
And that did the trick. May need to add a resistor to the circuit.
Close up of the test unit. I made a video in the next post
Mike, where on the column does that connector attach (the three contact pins that you cleaned)? Is it part of the clock spring or separate on the back of the steering wheel? Oh- on a 1990.
That pic was specific to an 87-89 car. You can see here with wheel removed.
I know the 93 cars have a true clockspring like most modern cars but I think 90-92 are somewhat in the middle. It’s been a while since I’ve pulled the wheel off a 90+ So I forget .
Here’s the plate off a 1990
You may want to make sure the cruise control cable is properly adjusted. I believe if there is too much slop, it will cause the cruise to surge up and down.
Pop the cable off the throttle body. On the cruise control part of the cable there is a small clip you can remove to take out some slack. Reinstall the cable and try it again.
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Exactly. I press it once to set but instead it keeps accelerating like it’s being held.
I haven’t considered that. But I would figure if it was the case then when turning the CC on it would automatically start the acceleration but I still have to press the button now.
Not necessarily, but you do make a point.
But it is the simplest thing to check right now. I would remove the column trim and find the plug with the CC wiring and use a meter to check the resistances of the button presses to see if the button is in fact sticking after...just to rule it out.
When vacuum is applied to the servo, it will pull the linkage in a way that adds more throttle. So either one of two things are happening. Something in the electrical portion of the system is commanding the system to apply more throttle, or the servo is unable to properly control vacuum. Unfortunately I don't have a good method to test the servo on the car without possibly trying the Rotunda tester.
