TMAP sensor voltages - Asking for a favor via some of your time.

Raptor04

Lurker
May 15, 2020
21
4
0
Can someone please check their stock or 3.5 bar tmap sensor voltages at the harness where it connects to the tmap sensor with a multimeter and report back the voltages of the yellow wire, yellow/blue wire, and yellow/red wire?

I am trying to diagnose why my car throws a 2abc fault code, which triggers the 1/2 engine light, with the 3.5 bar sensor upon initial startup, but the 2abc code and 1/2 engine light go away after immediately restarting the car and then the car runs normal.

I have checked continuity and voltage at the dme and harness. All wires have good continuity from dme to harness to include the ground. The yellow wire and yellow/blue wire show ~5.03v while the yellow/red wire which is the temperature sensor shows ~3.5V. These readings are with the ignition on, but car not started yet.

I have changed out the 3.5 bar sensor once already. I am running IJEOS MHD flash tune only with custom tune with voltage scaling adjusted in the tune and have the 3.5 bar option checked in MHD.

Curious if the above voltages are normal for the stock sensor and others using the 3.5 bar sensor.

Thanks in advance for anyone who can provide voltage info or has any other ideas on how to possibly resolve.
 

rac

Corporal
Nov 14, 2016
236
132
0
Australia
Ride
135i ST
I calibrated my TMAP recently against two other thermocouples but I don't have all the info on me, will look for it tomorrow.

Does the IAT temperature makes sense? If its reading 3.5v signal sounds like that is a cold temperature.
 

Jeffman

Captain
Jan 7, 2017
1,495
547
0
Also check your wiring. The wires leading into my sensor on the manifold started to fray from the wire bundle sitting on top of it and I was getting codes / half engine light on startup.

Also, here are some notes I have for 2ABC:
2ABC:
2ABC Charging pressure sensor, electrical
EXPLANATION: ECU lost connection with tune. Unplugging map sensor or tune with ECU awake will cause this. As will various other tuning related problems.
FIX: Clear code. If it comes back, check tune related wiring and consult with tuner.

GOOD LUCK!
 

Raptor04

Lurker
May 15, 2020
21
4
0
Also check your wiring. The wires leading into my sensor on the manifold started to fray from the wire bundle sitting on top of it and I was getting codes / half engine light on startup.

Also, here are some notes I have for 2ABC:
2ABC:
2ABC Charging pressure sensor, electrical
EXPLANATION: ECU lost connection with tune. Unplugging map sensor or tune with ECU awake will cause this. As will various other tuning related problems.
FIX: Clear code. If it comes back, check tune related wiring and consult with tuner.

GOOD LUCK!
Thanks. Did you get 2abc code with this? Sounds like you are referring to the map sensor and not the tmap sensor.
 

Jeffman

Captain
Jan 7, 2017
1,495
547
0
Yes. MAP sensor on manifold. It was 2ABD. Kind of related to your issue, no?
 

rac

Corporal
Nov 14, 2016
236
132
0
Australia
Ride
135i ST
I calibrated my TMAP recently against two other thermocouples but I don't have all the info on me, will look for it tomorrow.

Did not find my notes. But Blue/Yellow for me was the 5v supply so that is ok.

With ignition on, engine off, you should see the correct voltage for the ambient conditions on Temp and MAP signal wires from the TMAP and in turn the correct ambient conditions at the ECU. i.e. 1bar MAP and whatever your ambient temperature is (assuming the engine is cold). That's the fastest way to sanity check the sensor and wires.
 

Raptor04

Lurker
May 15, 2020
21
4
0
Did not find my notes. But Blue/Yellow for me was the 5v supply so that is ok.

With ignition on, engine off, you should see the correct voltage for the ambient conditions on Temp and MAP signal wires from the TMAP and in turn the correct ambient conditions at the ECU. i.e. 1bar MAP and whatever your ambient temperature is (assuming the engine is cold). That's the fastest way to sanity check the sensor and wires.
Thanks!
 

Raptor04

Lurker
May 15, 2020
21
4
0
Ok, here's my latest diagnostic on this. If I start the car without turning the ignition on first, e.g. press brake pedal and then push start button, the 2abc code and 1/2 engine light do not appear on startup even after letting the car sit. However, if I turn the ignition on first, e.g. push start button without pressing brake pedal, and then start the car, the codes appear.

Any ideas on what would cause this?

The good news is I have a partial solution to avoid the issue altogether but won't be able to turn on the dash lights without turning on the engine if I want to avoid the codes.

Now wondering if its a coding issue with the frm or kombi or some other module causing the issue.
 

Raptor04

Lurker
May 15, 2020
21
4
0
Another update. I can start the car with the ignition in accessory position #1, e.g. pressing the start button once without pressing the brake pedal without getting fault codes.

If I press the start button twice without pressing the brake pedal, this puts the car in ignition accessory position #2. Starting the car from this position results in the 2abc fault code and 1/2 engine light. So something that only turns on in the accessory #2 position is triggering this error.

Any ideas what it could be. Sounds like accessory position primes the fuel pump. Not sure if this could be related.

Any ideas on possible causes from being in accessory position #2?