pin #7 ground, on 90 tsi ecu harness

[patriot]

posted this on another forum, would like to get feedback from here too.
1g ECU Pinouts 7, 19, 24

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showing grounds are #24 ... obvious, and #19. i have a ground on #7 though, according to the ecu pinout for a 1gT, that is the ac switch... and i have no ac... i just wanted to make sure that those are the only two pins that should be grounded. could this one ground on the ac switch possibly havae destroyed the previous ecu?

her's a link

ECU pinouts for 1G turbos1G T http://www.vfaq.com/mods/ecu-harness-1G.html


well, i need the external schematic though to find out what pin 7 goes to. from what i understand on my orig ecu, we may have damaged it when messing around with that splice... damaged it beyond the original problem that is. that 2nd problem is fixed now, but the orig one still exists. now the first thing i have done, was to compare the resistance readings on all the pins to the other 1g ecu pin in the gsx. everything is exactly the same except for pin 7. on the talon, have a 3 ohm ground. on the gsx, the good one, i have no ground whatsoever. i go to the pinout chart and it says air conditioning switch. here is the thing that gets me. pin #6 says idle position switch, which is what i thought pin 7 was when i first looked at it. so the first thiing i did was, go to the throttle body, pulled the connector from the idle position switch, and guess what happened? i check the ecu pin 7 for ground, there is none. i connect the idle position switch back together... recheck pin 7, 3 ohm ground has returned.

ok now here is where im getting confuzzled. i go through this same process on the gsx. there is no ground on pin 7 at the ecu plug. you disconnect the idle pos switch and check the switch itself and you have a 40 ohm ground. on the talon, it is indeed a 3 ohm ground at the switch, which remains on the pin 7 at the ecu plug when reconnected.

have i confuseed everyone enough yet, ? essentially, i need the external schematic of pin 7 from the ecu harness, so i can see exactly where that particular wire goes throughout the talon. the only thing i can figure is that there is a bridge or something somewheree that is faulty. which might be why even though there is an actual ground on both of the switches, i can only see it at the harness on the talon and not the gsx. any help would be much appreciated.

 

[DSM90AWD]

Are any of the sensors on the thermostat housing disconnected or missing/have broken wires?

The very top sensor on the '90 Housing is the A/C swich, which may (I'm not sure) connect to the #7 pin you speak of. Should be easy to test though.

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[patriot]

unplugged that one, made no difference. it only seems to be the idle position switch. the thing that gets me is that it is supposed to have a ground on the actual sensor. but i have the ground showing up on the ecu pin. i thought it was supposed to be 5V, according to chiltons . i just dont want to hook up a new ecu and end up frying it.

 

[steve]

You can't just measure resistances on ECU pins. Some are inputs, some are outputs, some have pullups to 5v, some to 12v, and some had pulldowns to ground

Pin 7 is for the AC (the circuit is in the FSM and Tech Manual)
Pin 19 is the throttle position sensor input
Pin 24 is the sensor ground.

I can't quite figure out why the IPS fits into the question.

Steve

 

[dieseltech]

From what i gather from the wiring diagrams pin 7 is an input from the AC engine coolant temp switch which is in series with the Dual Pressure Switch. So this is not a ground. When your ignition is on there should be voltage there givin that your A/C Dual pressure switch is closed and so it the A/C coolant temp switch. The power for these switches is from Sub Fusible Link6 which is a 12v supply.

 

[blackrosenova40]

Hey dieseltech, I take it your a diesel mechanic. Where did you go to school?

I am currently enrolled in Hennipen Technical college's diesel mechanics program, second week in . Hennipen Technical is in Brooklyn Park Minnesota.

 

[dieseltech]

Yeah, Im a diesel tech. I went to Iowa Western Community College. I graduated from the ACDelco TSEP program. Although I've been educated in gas engines, I prefer diesel engines. Much easier to diagnose and such. I have found that being trained in gas engines has given me a large advantage as diesel engines are a little behind gas motors and so are the technicians!! Good luck to ya!

 

[blackrosenova40]

I have to agree that diesel techs are a lil behind in the times. It appears that it will soon change since from what I hear, emmisions laws are soon to become alot tighter in diesel motors.


I find it funny, I actually had to explaine to my instructor as to what an egr system does in order to reduce the amount of NoX in the exhaust. He told me it was to remove an amount of air in an intake system which would cause emmisions to go down because of the lack of air.

I told him it was to add exhaust back into the intake tract and reduce the tempature of the combustion process, therfore reducing the heat reaction creating Nox , and he just looked at me funny like WTF

 

[dieseltech]

. awesome.