1995 Cadillac EL Dorado cruise control

CRESTMARK

MEMBER
1995 CADILLAC ELDORADO
V8
FWD
AUTOMATIC
190,000 MILES

The mechanic has put in 4 new servos in an effort to solve this problem.
Codes are P061 and P062. Under history currently.
The behavior is that from time to time the cruise control won't work. So I turn the ignition off and restart the car. Sometimes it takes twice (restarting) instead of once to get the cruise to work. When it doesn't work I still get "Cruise Engaged". If I turn off the cruise control with the switch to try to get it to work, there is no response (doesn't say "cruise engaged) and still doesn't work.
This past week here in the Raleigh, NC area when the temperature was in the teens, the cruise wouldn't work unless I restarted the car a couple of times. This is even after the car was up to normal operating temperature. Since the weather is warmer the cruise is working again on the first try.
Any ideas? I have also turned the switch on and off to either make it work or to see if it would cause the cruise not to work. It seems to me like it may not be the servo, even though it works for a period of time after changing it out. The problem reacures anywhere from 3 months to over a year since replacement.
So far the mechanic hasn't been able to check the car without the cruise working. Or plan is to bring the car in the next time it isn't working. Not shut the car off so that the system won't "reboot".
Please help!

3 Replies

FACTORYJACK

MECHANIC
4,159 POSTS

That is the best idea, having it looked into when not working. There are several circuits involved that could be causing the problem. Are there any other pcm codes that could be inhibiting operation.

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Thursday, January 14th, 2010 AT 10:24 PM

CRESTMARK

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2 POSTS

No other PCM codes

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Friday, January 22nd, 2010 AT 2:59 PM

FACTORYJACK

MECHANIC
4,159 POSTS

Your P060 and P061 have relevance, here is some information.

P060
CIRCUIT DESCRIPTION
Code P060 will set if the cruise control is engaged and the transaxle pressure switch is indicating that the transaxle is in PARK or NEUTRAL.

TEST CONDITIONS
Cruise control enabled.
Cruise control engaged.
FAILURE CONDITION
Transaxle pressure switch input to the Powertrain Control Module (PCM) indicating transaxle in PARK or NEUTRAL.

ACTION TAKEN
PCM disengages cruise control.

NOTES ON FAULT TREE
Checking if Code P028 or P091 are set because they can cause P060 to set.
Checking if the PARK/NEUTRAL input to the PCM from the transaxle range switch agrees with the transaxle pressure switch. If they agree the transaxle was in PARK/NEUTRAL at code set, the code was driver induced by shifting into PARK/NEUTRAL while cruise control was engaged. If they differ, check for an intermittent fault.

P061
CIRCUIT DESCRIPTION
Code P061 will set if the Powertrain Control Module (PCM) output PO08 is commanding the vent solenoid "OFF" and the feedback is indicating that it is "ON" or if the PCM is commanding the vent solenoid "ON" and the feedback is indicating that it is "OFF."

TEST CONDITIONS
Test continuously.

FAILURE CONDITIONS
Cruise vent solenoid commanded "OFF" and solenoid feedback indicating the solenoid is "ON" for 0.5 second.
OR
Cruise vent solenoid commanded "ON" and solenoid feedback indicating the solenoid is "OFF" for 0.5 second.

ACTION TAKEN
PCM disables cruise control.

NOTES ON FAULT TREE
Checking if the cruise control servo is bad or if the control circuitry is bad. The frequency should cycle between zero and a not zero value. If the Digital Volt Meter (DVM) stays at zero, it must be a circuit fault or the PCM.
Checking for a short to voltage on CKT 403.
Checking CKT 451 for an open.
Checking PCM's ability to control the cruise control servo. The voltage should cycle between 0 and 12 volts. If it does, check CKT 403 for an open.

The P060 relates to transaxle pressure switch, inside the trans pan. The 61 vent solenoid is part of the servo. Since you have had 4 of these, I would say it is not a solenoid. You might opt to have the pressure switch replaced as process. If you need the transmission serviced, or have another reason to go in the pan, I don't think the switches are that expensive.

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Friday, January 22nd, 2010 AT 11:46 PM