Mechanics

TROUBLE CODE 15 CTS SIGNAL HIGH VOLTAGE

1984 Oldsmobile Ciera • 6 cylinder FWD Automatic • 100,000 miles

Rebuilt southern car throws trouble code 15. Replaced thermostat sensor as part of rebuild. Only other issue is high idle for couple seconds at startup and upon parking after driving. No idle issues during driving. High idle issue does not happen if I disconnect high speed control motor. Don't know is this is a separate issue or an indicator of an electrical/wiring issue.
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TheSandman
September 17, 2011.



So you replaced the coolant temp sensor already?If so what color were the wires going to it?Also do you have a multimeter?


Saturntech9
Sep 17, 2011.
High idling at start up is normal as the engine computer is designed to increase the idling speed and then lowers according to engine operating temperature.


KHLow2008
Sep 17, 2011.
To KHLow2008's response. That there is a higher idle at cold start up. I understand and expect. But it does not explain why it does it after driving and placing in park before shutting engine down. Engine is at normal operating temperature and a high idle would not seem necessarily need to engage (even for a few seconds). To restate, neither situation happens if I unplug idle speed motor (but that seems to defeat the purpose of the control).

To saturntech9, yes the coolant temp sensor has been replace and the male plug (to the sensor) that came with it had two black wires coming out of it(at least the plug had been replaced sometime before I got the car because it was wired into place), but I will get the color of the wires coming out of the wiring harness tomorrow when I get the time to go to the car. And yes I have a multimeter.


Tiny
TheSandman
Sep 18, 2011.
Alright get me those colors we could have a issue with poor connector replacement causing that code. Keep me posted with the colors and we will start tracing wires. Your scanner doesnt read live data on your car does it?


Saturntech9
Sep 18, 2011.
When the engine is shut off, the ISC would be be stopped at the cold start position. The computer does not have any idea of the condition of the engine operating temperature and when restarting, the computer would normally increase the air fuel ratio for a few seconds until it gets the the required data from the various sensors.

Tuen ignition switch on and wait 2 seconds and strat to see if problem persists.


KHLow2008
Sep 18, 2011.
To saturntech9: The wires coming out of the wiring harness are solid yellow and solid black (or an extremely dark color that appears to me to be black). I have continuity from both wires from the wiring harness to the plug. I sent my meter on 12v and had a reading of 2.5 from the yellow wire out of the harness and it the plug. No reading from the black wire.

To KHLow2008: Turn ignition key on for several seconds but no change in cold start up (increased rpm's for a couple of seconds before returning to normal idle), the car is parked in a garage with a 60 to 70 degree temperature range. Did you want me to run car to normal operating temperature and test to see if idle increases upon parking the car using your 2 second wait time on start up?


Tiny
TheSandman
Sep 19, 2011.
Does your scan tool read live engine data?I think the high idle could very well be related to the code 15 that is being set. So if we track the code 15 down it just might fix the idle concern.


Saturntech9
Sep 20, 2011.
Here is the trouble tree for the code 15 let me know what you find.


Saturntech9
Sep 20, 2011.
When I click on thumbnails they are obscured by the message reply box. Can you send them to my email address?
Sanfordgray@comcast. Net


Tiny
TheSandman
Sep 20, 2011.
I emailed you the trouble tree let me know what you find.


Saturntech9
Sep 20, 2011.
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