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I think this is the other part of that fuel purge / recovery system in the rear:
I find it strange to read 5.6V. I would have expected either ground/0V when the charcoal Canister was being purged (I.e. valve activated) when the measurement was taken or not give a reading, when the valve was not being activated.
I think this is the other part of that fuel purge / recovery system in the rear:
I find it strange to read 5.6V. I would have expected either ground/0V when the charcoal Canister was being purged (I.e. valve activated) when the measurement was taken or not give a reading, when the valve was not being activated as then that pin would not be pulled to ground through the ECU.
Or am I missing something?
Good job on measuring all terminals and documenting it nonetheless!
I find it strange to read 5.6V. I would have expected either ground/0V when the charcoal Canister was being purged (I.e. valve activated) when the measurement was taken or not give a reading, when the valve was not being activated as then that pin would not be pulled to ground through the ECU.
Or am I missing something?
Good job on measuring all terminals and documenting it nonetheless!
Think about it like this::::
You have a 12v power wire and a control wire,.... when testing the plug if you have a "true ground/0v" on the control wire, when you plug in the connector the valve will actuate.........to deactivate.. the DME must undo the true ground,.. that leaves a floating ground or floating voltage that has no real potential/amperage capabilities..hence it can read just about any voltage but has no potential to do work/amperage, some transistors can pull to ground very well but can have residual floating voltage that causes no harm but can be very misleading if you don't test for amperage
Last edited by Porschetech3; 09-04-2023 at 12:08 AM.
You have a 12v power wire and a control wire,.... when testing the plug if you have a "true ground/0v" on the control wire, when you plug in the connector the valve will actuate.........to deactivate.. the DME must undo the true ground,.. that leaves a floating ground or floating voltage that has no real potential/amperage capabilities..hence it can read just about any voltage but has no potential to do work/amperage, some transistors can pull to ground very well but can have residual floating voltage that causes no harm but can be very misleading if you don't test for amperage
Thanks for the explanation! I'd thought along those lines with the 5.6V being typical for semiconductors but didn't know that it would show like this when not pulled to ground.
So it looks like I had a couple components mixed up, good and bad. I'm pretty sure this is actually the Idle Positioner and voltage is good, traced back to x59/1 pin 8 as expected.
And this is actually the Throttle Plate Angle, 5v is correct. Toned out to x59/2 pin 22. Then goes to the 5v supply from the DME on pin 53. Traced all the way to x2/5 pin 16 where it goes to Differential Pressure.
I have checked the fuel injectors now, 12.x volts. It seems I have correct power on everything I've checked.
Today I've been checking the fuse box for about the third time, seems good on all fuses involved in engine management but I found one strange issue.
On Fuse C3 going to the Alarm Module, I can reach ground on the feed side (Top). These two RE/BR wire supply power to the module.
I have battery voltage on the supply side of C3 (Bottom). Also, The module seems to be working fine. Also interior lighting which goes out when the fuse is pulled.
I would think if it was shorted to ground that the fuse would blow instantly?
Something else I thought of is that the Airbag control module has been swapped with same part# from a donor. I've seen posts saying it was swapped and worked fine and others saying it has to be reset / married to the car. Would that cause the DME to not let it start, or just throw a warning? Original got wet, wasn't seen by Durametric, new one is seen & error free according to Durametric.
Can anyone confirm if the Airbag module has not been reset / activated it would cause the DME to not let the car run?
Not 100% but u have never seen an abs modual interfere with starting.
Thanks, I was thinking if the donor 996 was in a crash, the Airbag module would probably shut off the fuel pump.
But I don't know if that is a function handled by the Airbag module. Also you would think Durametric would show an error with the module.
09-03-2023, 03:38 PM
