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Author Topic: Throttle body actuator fault>voltage? solved!  (Read 4743 times)
TijnCU
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flying brick


« on: December 20, 2014, 04:18:03 PM »

Hey guys, I am stumped by my car. (2000 1.8t ME7.5 512) Flashed my revised maf file, try to start the car and... does not fire! I check the codes, there are multiple codes related to the throttle body. They will not clear and I have no response from the pedal. Does not adapt, and does not start. I then took out the ecu, placed my stock ecu and get the same issue.
The TB is clean, wires are all giving proper voltages (5v @ pin 2-gnd and 5v @ pin 2-6), when logging measuringblock 62 I get 2 working graphs for the pedal sensor, and 2 inverse graphs for the TB angle sensors when I move it by hand. I took it apart, looks very clean inside. scrubbed the brushes a bit and did a test on a seperate power source (11v) and the throttle valve will open/close very fast and strong.
When I put it back in the car, I can hear it whizzing when I switch ignition on, but it does not open or close as usual (pre start adaption). If i press the accelerator I can hear it "click" but it is not strong enough to open.
What voltage is sent by the ecu to control the motor? Is it 12v or 5? I did a quick test with my DMM connected to the plug pin 3+5 (motor power supply) and I get a quick flash of 7.4v on the screen. Now this is not a quick or expensive multimeter so it might not be a really precise reading.
Could it be that the motor requires 12v but is only seeing 7-8v because of a wiring problem? Or do you guys have other experiences with this sort of error? I could buy another TB, but if the problem is in the wiring or ecu thats a waste of money and time. Especially since I have working angle sensors AND a verified working motor on 12v...
Please share your thoughts!
« Last Edit: December 22, 2014, 06:53:40 AM by TijnCU » Logged

TijnCU
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flying brick


« Reply #1 on: December 22, 2014, 04:09:42 AM »

I hooked my battery to the charger last night, and this morning I am (with charger attached) able to control the throttle again! Definately a resistance problem, battery was 12.5v during previous tests, now it is 14.4. Anybody knows what incoming 12v source is used to control the throttle? this info is not specified in ElsaWin.
***
ECU pin 121 was getting too low voltage due to a bad fuse! Problem solved  Smiley
« Last Edit: December 22, 2014, 06:54:40 AM by TijnCU » Logged

fknbrkn
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« Reply #2 on: December 22, 2014, 08:20:16 AM »

i has the same problem after washing engine bay
checked TB wires and connectors - all ok
problem dissapeared next morning
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TijnCU
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flying brick


« Reply #3 on: December 23, 2014, 02:30:38 AM »

Turns out I didnt fix it with the fuse after all, the engine relay (30) had a small crack in the solder. Resoldered it and now everything is perfect!
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nyet
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« Reply #4 on: December 23, 2014, 11:02:26 AM »

Nice! Good job tracking down the issue, stuff like that is often hard to find.
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