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View Full Version : I removed my air conditioning now the check engine light is on. How do I eliminate it??



shreddr69
10-03-2011, 11:19 PM
I have an 88 st165. I removed the AC and a check engine code came up. Does anyone know what to do to bypass the AC plug that run to the ECU? It's code #51, which is said to be TP sensor, AC switch, accelerator cable, or any combo of the 3 as far as I can tell and since I pulled the AC, that is my first logical choice. Any ideas would be most appreciated. Thanks!

KoreanJoey
10-04-2011, 04:07 AM
Plug back in the AC switch? It's located on the one of the pipes on the right side.

shreddr69
10-04-2011, 06:37 AM
I removed the pipes. They were in the way of what was going on in the engine compartment. Any other ideas? Can I short them out or use resistors to cancel the engine code?

KoreanJoey
10-04-2011, 07:11 AM
Um... probably but you'll have to get a BGB to find the resistive value of the switch.

The Captain
10-04-2011, 12:24 PM
Just jumper it and see what happens. I do this to charge a system.

alltracman78
10-04-2011, 07:20 PM
Plug back in the AC switch? It's located on the one of the pipes on the right side.
You should know better. The pressure switch has nothing to to with engine codes. And nothing to to with the IDLE circuit.


Normally Code 51shouldn't come up. It's not a diagnostic code, shouldn't turn the MIL on, and should only show up when TE1 and E1 are connected and either the ECU isn't getting an IDL signal or the ECU is getting an AC on signal.

If it turned on your MIL you may have a bad ECU.
But I would check your ILD and AC signals first.
With the key on and throttle closed you should have zero volts at the ECU [pin 13? in the middle connector, pink? wire].
If you have 12V [or 5V, I can't remember which for that] make sure your throttle cable isn't pulling the throttle open at all [you should have a very small bit of play in the cable].
If that's ok you may need to readjust your TPS, you may have a bad wire, or your TPS is bad.

You should have zero volts at pin 20 on the largest? connector. Black/white wire. That's the AC on signal. 12V means the AC is on [or the ECU thinks it is], 0V means it's off.

If both those check out most likely you have a bad ECU.

shreddr69
10-05-2011, 05:20 AM
What is the MIL?

alltracman78
10-05-2011, 03:03 PM
Malfuction Indicator Light/Lamp.

It's just a different name for the CEL, I'm used to using it from work.

KoreanJoey
10-07-2011, 04:59 AM
You should know better. The pressure switch has nothing to to with engine codes. And nothing to to with the IDLE circuit.


*shrug*

But I did not. But now I do. :)

shreddr69
10-16-2011, 06:09 AM
Yeah it was the TPS. I replaced it and adjusted it and all is well ;) thanks!!