Where's the damn idle switch?

boostjunkie · Post by **boostjunkie** » Sat Jun 07, 2003 6:45 pm

I finally ended up washing my car yesterday and decided to spray down my engine bay. The only problem is that when I started the car, I got two CE codes. 22 and 42. My question is, where's the idle switch (code 42)?

A 12 year old car has A LOT of chewed up wiring

legazee · Post by **legazee** » Sat Jun 07, 2003 8:11 pm

boostjunkie the haynes manual sez that our year model 90-94 have an idle switch in the throttle position sensor......but it sounds like u got some spray that got into a connector. i was cleaning around the turbo and back of the motor and had things bagged but i still managed to get something wet that should not have gotten wet and now i get check engine light as soon as i crank it up. after it warms up and the idle stops being screwy the light goes off the car runs great and no light until the next crankup. i will have to disconnect each coupling and spray them with electric gremlin fixer to remove all the moisture. if u haven't checked the intake forum lately i have the blue subie intake on my car now and have been giving it the runthru.....works better than the other one did and looks a lot better. i will try and post a pic or2 this weekend.

entirelyturbo · Post by **entirelyturbo** » Sat Jun 07, 2003 8:51 pm

The idle switch code is most likely related to the IAC valve. I got that code when I put mine back together wrong...

I did a de-grease once and sprayed the engine down. Afterwards, I had codes for the O2 sensor, starter switch, purge valve, idle switch and VSS. So yes I know very well how important it is to cover various sensors with plastic bags.

vrg3 · Post by **vrg3** » Sat Jun 07, 2003 8:58 pm

The idle switch is built into the throttle position sensor. It basically tells the ECU when your foot is off the accelerator pedal completely.

You may want to remove the TPS and blast it with compressed air to make sure you dry up any water that may have gotten in there; it could be shorting the idle switch.

entirelyturbo · Post by **entirelyturbo** » Sat Jun 07, 2003 9:02 pm

Okay, so vrg3, when I screwed up my IAC valve, do you think it pissed off the TPS or something?? Because the IAC only opens when the throttle plate is closed, so if that is messed with, then the TPS is confused...

I do know our cars kinda have a tendency to get 5 sensors angry when only 1 has a problem...

vrg3 · Post by **vrg3** » Sat Jun 07, 2003 9:11 pm

I don't see how the IAC valve malfunctioning could make the ECU believe the idle switch is malfunctioning...

That doesn't mean it can't happen though. Most of the logic the ECU uses to determine whether or not a sensor is trustworthy is rather opaque. It could be using really circuitous methods. For example, it's possible that when idling with the idle switch on, the ECU computes an expected airflow based on the current IAC valve duty cycle, and then if the MAF sensor reads much higher than that expected flow, it throws a code. That basically means that a problem with the IAC valve, idle switch, or MAF could result in any of the three codes.

rsstiboy · Post by **rsstiboy** » Sat Jun 07, 2003 10:57 pm

there is an easy solution to all of your problems..... DON'T CLEAN YOUR ENGINE!!

boostjunkie · Post by **boostjunkie** » Sun Jun 08, 2003 2:00 am

Thanks for the help, guys. I'll need to check the wiring again. All I know is that the ca was idling really rough, and would even stall out last night.

This morning we got a crapload of rain and I couldn't even start the car!! The starter would turn but the engine wouldn't catch. I checked the fuel pump for activation, and tried fiddling with the wires under the hood. No dice

I hate rain!!

Post by **Legacy777** » Sun Jun 08, 2003 7:49 pm

the idle switch is in the TPS

Here's a couple scans.

the testing 3 scan is the one you want to pay attention to.

http://www.main.experiencetherave.com:8 ... ns/TPS.jpg
http://www.main.experiencetherave.com:8 ... sting1.jpg
http://www.main.experiencetherave.com:8 ... sting2.jpg
http://www.main.experiencetherave.com:8 ... sting3.jpg

ciper · Post by **ciper** » Mon Jun 09, 2003 7:06 pm

I clean my engine often.

First thing Id do is remove the connector and dry it out. Many of these connections have a rubber seal. Water under high pressure can get it but will never evaporate out.

Take the time to adjust your IDLE switch properly. If you dont it will also effect WOT, even changing the behaviour of the AC clutch disengauging!

ciper · Post by **ciper** » Tue Mar 30, 2004 6:31 am

I just wanted to tell everyone that in this image

http://www.main.experiencetherave.com:8 ... sting2.jpg

You are measuring for .028 connected and .035 open AT PORTION G(bottom right) not the screw with the spring!!! A common mistake

boostjunkie · Post by **boostjunkie** » Fri Apr 02, 2004 3:40 pm

Hehe. I did the screw measuring thing at first and then figured out I had to get to the place behind the throttle body.

kleinkid · Post by **kleinkid** » Mon Dec 28, 2015 8:40 pm

I adjusted my TPS on 91 SS last week. Did a real good job feeler gages at that upper screw with spring. All wrong. Looked at the picture and did it wrong. Sure is easy to get at there, though!

Ciper post showed me how. So obvious now, not sure why I did not see that first time.

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Where's the damn idle switch?

Where's the damn idle switch?

idle switch location

Re: Where's the damn idle switch?