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The Townsend site has a good list for the cruise control ECU pins for older models, however, it isn't accurate for the 92+ models. Here is an updated version for these models that I compiled for troubleshooting electrical problems on my car ('94 5-spd). This information is a composite of the wire colors from Townsend and the wiring diagram and cruise control chapeter from Bentley. All comments/corrections are welcomed, especially corrections for automatics (I'm biased toward 5-spds).
The cruise ECU takes inputs from the speedometer and the SET-RESUME-TIP stalk switch, and the brake/clutch switches. It uses this information to send 12v and ground signals to the vacuum pump which causes the throttle to accelerate, hold or drop to idle. For safety, the ECU has multiple ways to disengage cruise and return control of the car to the driver: Brake and clutch pedals (on manual) have both vacuum and electrical switches, either of which cancels cruise control. In addition, on '89+ models, cruise is cancelled if the brake light switch closes or if a brake light bulb is burned out.
The 92+ models have a 16-pin connector and uses pins 1, 3, 4, 5, 6, 7, 8, 9, 10 and 11. The sends to the vacuum pump (pins 1, 6, and 7) and the speed sensor (pin 11) can be checked by back-probing the ECU connector with a multimeter when the car is moving above 23 mph. All other pins can be checked while car is stationary. Here are the assignments:
PIN 1 Red wire
Sends 12v supply to pin 3 of vacuum pump when CRUISE on and speed is above 23 mph. 12v send is removed when brake or clutch depressed or cruise turned off.
PIN 3 Green wire
Sees 12v when SET on, causing ECU to send ground out of pin 7. When SET is released, ground is removed, and SET speed is stored in ECU until cruise is switched off, speed drops below 23 mph or ignition shut off.
PIN 4 Yellow wire
sees 12v when RESUME on. This causes ECU to send ground out pin 7, causing vacuum pump to run. When stored speed is reached, ground is removed
PIN 5 Red/white wire
sees ground from grounding point G3 when BRAKE LIGHT is OFF; sees 12v from fuse 31 via brake light switch when BRAKE LIGHT is ON.
NOTE: ECU will not turn cruise on if it does not see ground at this pin. The ground is fed to ECU via brake light bulb. If bulb is burned out, ECU will see open circuit instead of ground and cruise will not engage.
PIN 6 Orange wire
Sends ground to pin 1 of vacuum pump when CRUISE is on, causing vacuum switch at pump to close. Moving stalk switch to OFF or TIP, or pushing clutch or brake pedal removes ground from pin 1 of pump. This causes vacuum switch to open, releasing vacuum and allowing throttle to return to idle.
PIN 7 Grey wire
Sends ground to pin 2 of vacuum pump when SET is on, causing pump to run, pulling in throttle via regulator at accelerator pedal. Releasing SET removes ground from pin 2, causing pump to stop. At this point ECU takes over control of car, running vacuum pump if road speed is than SET speed, or allowing car to coast if speed is too great.
PIN 8 Black wire
Sees ground from grounding point G8
PIN 9 Red wire
Sees 12v from pin 1 of stalk switch when key on RUN, cruise ON and clutch and brake pedals released. If either clutch or brake switch is bad, you will not see 12v at this pin.
PIN 10 Brown wire
Sees 12v from fuse 8 whenever key is in RUN (manual)
PIN 11 Blue wire
Input from speed sensor at speedometer
posted by 65.56.16...
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