P2138 is only caused by the throttle pedal or bad wiring between it and the pcm.
Test the pedal and it's wiring to find your issue.
Test the pedal and it's wiring to find your issue.
P2138, won’t rev above 3000 rpms, lots of smoke
- Thread starter jsilva
- Start date
Thanks! I had been focussing on the fact that it happened right from the first start after I had done work which had the intake manifold off (and therefore the throttle body) and assumed it was something I did.
It‘d be nice if I didn’t have to take things apart again
Do you have any advice for testing?
It‘d be nice if I didn’t have to take things apart again
Do you have any advice for testing?
I had a look today and realised I’m not totally sure which connectors are being referred to in the service manual.
I’m assuming the one I circled is the connector with 3A to 3AA. But can I safely assume the other connector with 2A through 2AD is adjacent to the right (in the photo)?
That is seriously cramped! I’m not sure yet how I’m going to be able to get my hands in there and also see what I’m doing at the same time.
I’m assuming the one I circled is the connector with 3A to 3AA. But can I safely assume the other connector with 2A through 2AD is adjacent to the right (in the photo)?
That is seriously cramped!
I’m not sure yet how I’m going to be able to get my hands in there and also see what I’m doing at the same time.
Today I took out the front seat hoping to get more room, and indeed it gave me more room but the hump in the floor was killing my back. I was thinking I’d take out the PCM so it’s not quite as difficult.
However I’m unsure how to test the terminals. There is no space to wedge the test lead in to make contact with anything.
Am I supposed to make a hole in the wire housing? Seems pretty silly to require doing that just to test. Or am I missing something?
However I’m unsure how to test the terminals. There is no space to wedge the test lead in to make contact with anything.
Am I supposed to make a hole in the wire housing? Seems pretty silly to require doing that just to test. Or am I missing something?
These would be the easiest.
Or you can get some normal 1mm pin test leads that will fit in the back of the connectors.
Or you can get some normal 1mm pin test leads that will fit in the back of the connectors.
Thanks Ssinstaller. I went ahead and got a decent kit which includes a variety of test leads. A couple of years ago I got a nice set of leads for my Amprobe multimeter but I’ve only ever done home electronics troubleshooting (vintage amps, instruments) and didn’t even know about piercing leads or 1mm tips!
I tested the connectors today.
- 3D had smooth voltage as the APP was pressed, and in the voltage range according to the service manual.
- 2A had 1.3V (or so) and didn’t change with the APP. So obviously an issue there.
- I tested for an open circuit as the instructions say and everything was ok.
- I didn’t test for a short circuit. Partially because my back was really hurting by that point. Was that a mistake?
Since the error was in the first step (but the APP is clearly working), and there was no open circuit which means there is continuity from every APP pin to the PCM, and since this problem happened when I was fiddling around the throttle body, I’m guessing it’s the throttle body?
But what’s the likeliness two throttle bodies would stop working at the same time? I know it’s possible but I feel like I’m still missing something. Maybe it’s because I didn’t test for a short circuit?
- 3D had smooth voltage as the APP was pressed, and in the voltage range according to the service manual.
- 2A had 1.3V (or so) and didn’t change with the APP. So obviously an issue there.
- I tested for an open circuit as the instructions say and everything was ok.
- I didn’t test for a short circuit. Partially because my back was really hurting by that point. Was that a mistake?
Since the error was in the first step (but the APP is clearly working), and there was no open circuit which means there is continuity from every APP pin to the PCM, and since this problem happened when I was fiddling around the throttle body, I’m guessing it’s the throttle body?
But what’s the likeliness two throttle bodies would stop working at the same time? I know it’s possible but I feel like I’m still missing something. Maybe it’s because I didn’t test for a short circuit?
The wiring you're testing is for the actual gas pedal. If you have a circuit not showing the voltage as expected in the manual, that would mean your gas pedal is bad, not the throttlebody.
There are no shared wires between the APP and the throttlebody.
I would test for a short before replacing the pedal assembly.
There are no shared wires between the APP and the throttlebody.
I would test for a short before replacing the pedal assembly.
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The service manual says that if there is failure in the first step—if the two terminals don’t change voltage smoothly in response to the APP—that replacing the throttle body is the remedy. Replacing the accelerator is in the second step—if the voltages aren’t in range as the chart shows.
Since on mine the voltage doesn’t change on 2A in response to the APP I’ll never make it to the second step. So it’ll be either the wiring harness or the throttle body. (And it’d only be the wiring harness if I test again and there is a short.)
Or am I misreading?
Since on mine the voltage doesn’t change on 2A in response to the APP I’ll never make it to the second step. So it’ll be either the wiring harness or the throttle body. (And it’d only be the wiring harness if I test again and there is a short.)
Or am I misreading?
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This test is written pretty poorly.
But, I think step two is saying if the terminals 2a and 3d are behaving as expected and the throttle blade is not, then you need to test the TB and replace if it's found to be bad.
The voltage readings on pins 2a and 3d are 100% generated by the pedal, they should follow the voltages shown in the manual even if there was no throttlebody present. Also the throttlebody isn't listed as a possible cause for you MIL.
I just checked the pcm diagram to be sure, and there are no direct connections between the APP and the throttlebody.
I'd finish the wiring test and if you don't find any shorts replace the pedal.
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I follow what you’re saying Ssinstaller. Either way I saw an accelerator on eBay for cheap enough from a high volume and highly rated seller and so I went ahead and bought it. I’ll still do the remaining electrical tests... such a pain!
For testing for shorts, can I just use the cigarette lighter as a ‘power supply’? I’m not sure where else to use. Also, do I need the connectors out of the PCM for those tests as well?
For testing for shorts, can I just use the cigarette lighter as a ‘power supply’? I’m not sure where else to use. Also, do I need the connectors out of the PCM for those tests as well?
Power supply would be pin 2k at the pcm or pin A at the pedal.
Easiest way to test. Pull connectors from pedal and pcm.
At the pedal you should have:
No continuity between any pins.
No voltage on any pins.
No continuity from A, C,D,E,F to chassy ground.
Easiest way to test. Pull connectors from pedal and pcm.
At the pedal you should have:
No continuity between any pins.
No voltage on any pins.
No continuity from A, C,D,E,F to chassy ground.
Ok ... I finally got on to this.
The only thing I noticed, which may not be of significance, is that there was no continuity between APP pin B (or E) to chassis ground. I don’t know there should be, but in the manual it omits those pins when testing for a short circuit to ground.
Since none of the tests specified failed I went ahead and replaced the accelerator pedal, and it made no difference.
The only thing I noticed, which may not be of significance, is that there was no continuity between APP pin B (or E) to chassis ground. I don’t know there should be, but in the manual it omits those pins when testing for a short circuit to ground.
Since none of the tests specified failed I went ahead and replaced the accelerator pedal, and it made no difference.
That pin is the sensor ground it is connected to pin 2H at the pcm, it may be isolated from the body ground.