jmlee44
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- Feb 13, 2016
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Ok all experts!
I've been running down my cruise control issues following the Alldatadiy manuals and diagrams.
Here is where I am at: The cruise never activates. No light on the dash, doesn't try to accelerate - nada.
So I pulled the ECU/PCM under the glove box and with a pinout diagram I traced the following down:
When I turn the cruise switch on, I get 12v on the appropriate wire.
When I press set/coast, I get 12v on the appropriate wire.
When I press accel/resume, I get 12v on the appropriate wire.
I checked both brake switch inputs - both are closed supplying 12v until the brake pedal is depressed a good 1/4 inch.
I also back-fed 12v to the PCM output to the instrument cluster to verify the Cruise light on the dash works, it does.
The check engine light works, but it is not on when driving ( I heard a TPS code could cause in-op cruise). All brake lights work. TCC unlock works etc...
Now under the hood:
The vacuum cruise solenoid moves freely. If you apply 12v to the vent valve to close it, it will hold vacuum.
I ohmed out both solenoid's ...both were about 38ohms I think...in any case, in range per alldata.
I ohmed out the servo position sensor, open circuit. Gotcha I thought. I took the cruise servo off the car, took it apart and cleaned everything out and put it back together. Now getting 18 ohms on the sensor circuit - per all data 15-25 is good.
Put it back in the car - same symptoms, no cruise on light, no activity - nothing.
Unplugged the servo and re-checked all my ohm readings, all the same. Also checked power from the car side of the connector to the servo:
With the connector unplugged, I get 8v on both the vacuum and vent solenoid circuits if the cruise switch is on. 0v if off.
I get 5v on the servo position sensor circuit, whether the cruise switch is on or not.
Can anybody throw any suggestions on where to go next? I assume my VSS is fine the dash reads speed. Are the voltage readings at the servo unit normal? I would assume even if the vacuum part of the system wasn't working properly I would at least briefly get a cruise light. I get good solid vacuum at the servo. If I apply 12v to close the vent, it is strong enough to pull in the throttle.
Much appreciate the help!
I've been running down my cruise control issues following the Alldatadiy manuals and diagrams.
Here is where I am at: The cruise never activates. No light on the dash, doesn't try to accelerate - nada.
So I pulled the ECU/PCM under the glove box and with a pinout diagram I traced the following down:
When I turn the cruise switch on, I get 12v on the appropriate wire.
When I press set/coast, I get 12v on the appropriate wire.
When I press accel/resume, I get 12v on the appropriate wire.
I checked both brake switch inputs - both are closed supplying 12v until the brake pedal is depressed a good 1/4 inch.
I also back-fed 12v to the PCM output to the instrument cluster to verify the Cruise light on the dash works, it does.
The check engine light works, but it is not on when driving ( I heard a TPS code could cause in-op cruise). All brake lights work. TCC unlock works etc...
Now under the hood:
The vacuum cruise solenoid moves freely. If you apply 12v to the vent valve to close it, it will hold vacuum.
I ohmed out both solenoid's ...both were about 38ohms I think...in any case, in range per alldata.
I ohmed out the servo position sensor, open circuit. Gotcha I thought. I took the cruise servo off the car, took it apart and cleaned everything out and put it back together. Now getting 18 ohms on the sensor circuit - per all data 15-25 is good.
Put it back in the car - same symptoms, no cruise on light, no activity - nothing.
Unplugged the servo and re-checked all my ohm readings, all the same. Also checked power from the car side of the connector to the servo:
With the connector unplugged, I get 8v on both the vacuum and vent solenoid circuits if the cruise switch is on. 0v if off.
I get 5v on the servo position sensor circuit, whether the cruise switch is on or not.
Can anybody throw any suggestions on where to go next? I assume my VSS is fine the dash reads speed. Are the voltage readings at the servo unit normal? I would assume even if the vacuum part of the system wasn't working properly I would at least briefly get a cruise light. I get good solid vacuum at the servo. If I apply 12v to close the vent, it is strong enough to pull in the throttle.
Much appreciate the help!
