2000 Ram 1500 2wd 5.9.

Truck will run perfect without the AC. As soon as the AC is on it immediately throws a check engine light and throttle response diminishes. Off idle hesitation is slight to very bad. Heavy stumble (only when I depress the accelerator). If I get my foot into it it's better, but still lacking quite a bit of HP.

Code "PO123" (High voltage to the signal wire on the TBS)

I have swapped the TPS. (Nothing)
Fuel pressure is 45-50psi under load.
Replaced the IAC and cleaned the throttle body. (Nothing)

Any ideas would be greatly appreciated.

Thank you for taking the time to look....

 

According to the 2001 FSM, that code can be:

Throttle position sensor voltage high
- or -
Accelerator position sensor (APPS) signal voltage too high (I think this is for diesel only)

It looks like the TPS is supposed to run off of 5 volts... The output of the TPS back to the PCM is generlaly around 0.26V (idle) to 4.49V (WOT).

My guess is that you have some sort of short between your AC control line and your TPS output line back to the PCM. Check the output of the TPS both with and without the AC turned on.

Cartman

 

why even bother with AC? my truck has got it, but i never use it, i like my 350AC...

 

The compressor bearing or clutch or even the idler pulley bearing (with the extra load) might be bad.

Oh! And BTW! That's a very helpful response 95laRAMie! If it's broke don't use it! LMAO Maybe he wants to use it cuz it's HOT out! LOL

 

Thus far I have checked the voltage at the TPS. 5 volts at the unit. Signal wire is .5-3.5 volts and this is what it calls for.

I unplugged the connector at the compressor (so it would not turn on) and I get the same exact result.

What is happening is for some unknown reason as soon as the AC is turned on, the IAC goes haywire and throws a code. I assume that the IAC is wide open and will not adjust back in to the TB. Why?

Yes I would like to have AC... I live in the High Desert of Ca. It's only going to be 105 today.

Thanks...

 

Where did you buy the IAC and what brand is it?

 

IAC is perfect... 2 from Mopar and one from NAPA.

There is virtually 4 signal wires to the IAC and not a simple diagnostic.

4 Leads; nd two pull the seat open and two that push it closed.

No matter what there... why???? Will it run W/O the air?


Never mind... I got the IAC from 7-11. Is there a problem?

Zman... Tell me how two fix.

Hey Zman... tell me the protocol on testing this specific situation. I'm all ears. Obviously you know more about 'Brand" so due tell ALL what we need to use.

 

Sorry to bump an old thread. Found while searching

I have the same problem. 5v TPS seems like it is shorting out with the 12v AC power. When the AC comes on the TPS goes from 9.6% (at idle) to 100%. Turn AC off and it reads within spec.

I would like to rule out ECM and Wiring harness. Guess I need to check continuity between AC connector and TPS connector. Anyone know what the TPS power signal wire color is?

Thanks!

 

Kinda a stupid question but did u check the compressor to make sure the bearing wasn't bad and or it was partial locked up.

I had a car that did the same thing. U would turn the air on and idle would be rough and it would hesitate and no power. And my iacv was going to 100% to keep the car running because the strain on the motor.

 

You would most likely fry the pcm if that was the case. The tps has three wires going to it, ground, 5 volt supply voltage and return voltage to the pcm(less than 5 volts).