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Po2135

4K views 26 replies 9 participants last post by  gmcxt 
#1 ·
Throttle / Pedal Position Sensor / Switch A/B Voltage Correlation

This code has been seldom and randomly popping up on my buggy ever since I first got it running. I could never make it happen so I just kept erasing it but I've seen found 2 conditions in which I can make it happen reliably.

1. When I tow it to a ride and it has been on the trailer in the wind for a long time. It will be fine when I put it on the trailer but when I arrive to camp the code will be there the first time I start the engine. This hasn't happened every time but close to it. The colder the weather the more reliably it seems to pop up.

2. When I blip the throttle in quick succession rapidly 4 or 5 times it will throw the code every time.

When the code is triggered it puts the buggy into limp mode and ignores the pedal, thus I only get a weak idle.

My pedal is brand-new.
 
#2 ·
Pulled my TB and sprayed it out good with brake cleaner, concentrating on the joints where the throttle plate shaft rotates. I can not get the code to come back now. Hopefully there was just some grime or something built up in there causing a little extra resistance.
 
#3 · (Edited)
Could be the pedal connector/pin loose or loose wiring/pin at the throttle body connector, or a broken throttle body circuit not working intermediately when wiring is warm. The Gen III's had this problem with the wire from TAC to TB and was pretty common. It also could be the TB TPS itself. Might try another one if you have a spare for trouble shooting.

If it comes back focus on the harness. But its possibly (remote though) it could be the battery or a ECM connection to batt. If the battery had low voltage or the ECM getting low voltage. Then a battery voltage drop during the cranking cycle may cause the code to set and place the vehicle into the reduce engine power mode.

Check you battery voltage to the ECM while cranking to eliminate this.
 
#5 ·
Pretty sure its a safety feature, if the ecm doesn't have commanded TPS and actual TPS within a certain range it limps down for safety, if your blades were sticking then it would cause the delay the computer was seeing and shut you down.

There's a reason DBW TB's are sitting on the shelf at autoparts stores, they start sticking, throw a code, most shops toss another TB on it and away you go.
 
#6 ·
I have fixed a few with this code just by cleaning the T-body's good. I usually scope the pedal's and confirm they are good but most of the time the T-body is just shitted up. And yeah its a safety feature that they go into limp.
 
#10 ·
Have you done any other trouble shooting or just cleaned TB since it cam back. Might start checking things. If you removed the TB to clean it then I would start with the harness at the TB, you disturbed it enough for it to work a while.

What code reader do you have, can't remember?
 
#12 ·
Give me a little info on your engine, year and what it is out of. I am not at work but can look it up and talk to techs on friday. They even just releases a bulletin to replace the elec portion of the throttle body on 07-10 units. I will check on friday if you can wait that long.

Rob
 
#14 ·
Recommendation/Instructions:

Complete the current SI diagnostics for any symptoms or trouble codes found. If a intermittent T/P or TAC module type code is occurring complete the inspections below.

1. Inspect all related throttle body terminals for a loose wiring crimp. The loose crimp may be difficult to find, and the poor connection will be between the terminal and the copper strands of the wire. Wiggle test the individual throttle body circuits to see if the concern can be duplicated.

2. Inspect the related circuits for broken wires inside the insulation. The outer wire insulation may look fine, but the internal copper strands may be partially broken. Breaks in the wires usually occur within 1 to 4 inches of the throttle body connector. Wiggle testing may also induce a trouble code to set.

3. On C/K trucks complete SI procedures for voltage drop on grounds G103 and G104. Grounds G103 or G104 may be loose or corroded.

If a terminal crimp or a broken wire has been found, repair or replace only the circuits involved. There is a throttle body pigtail connector available through GMSPO, but installing this pigtail connector may cause other intermittent TAC module/TP codes at a later date. If this pigtail must be used, please follow the SI procedures for Splicing Copper Wire Using Splice Sleeves. (the proper Kent-Moore crimping tool must be used for this repair)

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


2005 Chevrolet SSR | SSR VIN S/T Service Manual | Document ID: 1869994
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#PIP3089B: SES Light And Reduced Engine Power DTC P0120 P0220 P1516 P2135 - keywords accelerator actuator APP blade body connector connection DTC L33 L59 LH6 LR4 LM7 LS1 LS2 LQ4 LQ9 module position reduce sensor - (Oct 31, 2006)

I hope this helps, it is all that I could find. We have replaced some of these connectors. We have also rewired the harness from this connector to where it plugs in. I think it is 6 wires about 10' each. Need new connectors and pin terminals.
 
#15 ·
Its back. Definitely has to do with being cold. The other day after replacing the tb it ran fine for hours and it was a warm day. I ran almost an entire tank of fuel through it. Tonight when it is cold it wouldn't run a full minute between clearing that code and throwing it again.

My first trip before the Trans died after it sat out in the cold it threw the code the instant i started it. Once it warmed up i drove the entire day without issue. that night when i got home and it was cold it threw it again.

I guess my next step is to go into the harness ... I tried a new pedal tonight also.

Sent from my DROID BIONIC using Tapatalk 2
 
#16 ·
This happened to me when driving our 'new' company van (08 Express van, 4.3l).

Lots of info came up when I was searching about wires being chafed, usually the yellow wire 1-4" from the throttle body connector.

When I dug into it, the harness had already been "repaired". I re-crimped all of the connections, and was unable (still have not been able) to get the issue to repeat itself. Good luck.
 
#17 ·
In general I suck with electrical. I can fairly easily wrap my brain around some of the most complicated subjects in the 4x4 industry but for some reason I just don't get electrical. I am learning a lot as a result of having this engine though and I am glad I did it. I am fortunate to have a shop-mate who is a guru and very patient and he had me check resistance of each wire from TB connector to ECM. All wires had 0 except two. Those two had various readings that jumped around a lot as I moved the TB end of the harness around. One was about 10x worse than the other. I removed their pins from the connector, re-crimped them for good measure, and tested them again with same results. This told me that the issue was somewhere in the harness so I ran new wires from the connector to the ECM and tested resistance again and they were both at a reliable 0. Plugged everything back in and she seems to be running great now. It was warm today so we will see what happens tomorrow in the cold morning air. If it runs good then I will say its resolved. (Again.)
 
#24 ·
I hope you have got it. We have only had to rewire about 5 of these at work in the past 10 years but we replaced 3 tb's last week on higher milage trucks.
 
#25 ·
Subscribing to this. Mine will post a Throttle position code at random kinda sounds like your symptom.

It is winter here so I am not running it anytime soon so I can't get the exact code.


Just for info my setup:
Ls6
Cabe TB
Once in a while it posts a throttle position code
Clear code will be fine for a while then it comes back
 
#27 · (Edited)
When it comes back heres some more info that might help

Circuit Description

The throttle position (TP) sensors 1 and 2 are located within the throttle body assembly. The TP sensors share a common 5-volt reference circuit and a common low reference circuit. The 5-volt reference circuit is also shared with the accelerator pedal position (APP) sensor 2. The 5-volt reference voltage is supplied on 2 separate engine control module (ECM) terminals, but the terminals are connected internally to the same voltage supply. Each TP sensor has an individual signal circuit, which provides the ECM with a signal voltage proportional to throttle the plate movement. When the throttle plate is in the closed position, the TP sensor 1 signal voltage is near the low reference and increases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. If the ECM detects that the TP sensors are not within a predicted value from each other, DTC P2135 sets.

If you can scope it you should be able to find it. Its faster than a multimeter and more accurate. I find electrical diagnostics so much easier when you can visually look at whats happening. I dont trust Datastream PIDS they dont always give you the data that is acually happening. Especially if your in open loop.

Since you did your own harness chopping Id go back and make sure there is no bad connections here and there on the TAC electrical connector ciruits. Ignore "ohms" and do voltage only. PCM doesnt see resistance it see voltage. Pull up your alldata and look at the TAC diagram. APPS2 and TPS1&2 both share the 5V Ref (circuit 41) like stated above. Hook up a 4 channel scope to pins D, E, F, C.
C should always be 0V.
E should always be 5V.
F starts at 4.5-5V and goes down in voltage as throttle opens. WOT less than 1V.
D starts at less than 1V and goes up in voltage a throttle opens. WOT 4.5-5V.

Gently tap on it with a large screw driver or feminin hammer......
Poor Ice water on it.....
Shoot it with a hair drier or heat gun....
Yank wires...

Edit--if you still have the TAC book i sent you on page 31 there is a case study about your code on an '05 2500 that was the wiring harness mentioned earlier.
 
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