PLEASE HELP - serious 'safe mode' problems!!!!
Discussion
And should add, that when checking any voltages etc if the ecu cannot log them all, you must use a scope.
Using a voltmeter is ok for a static reading of something. For a varying voltage you must use a scope otherwise you could easily miss a small glitch that a multimeter would simply never pick up.
Using a voltmeter is ok for a static reading of something. For a varying voltage you must use a scope otherwise you could easily miss a small glitch that a multimeter would simply never pick up.
Faults like this are very difficult to diagnose, metering wiring for continuity is not the best way but is easier than volt dropping wiring under load which is the correct way. Also all earths need to be checked and cleaned , these days a lot of cars rely on the thread of the bolt for contact as paint is still present under terminals.
EssexVXR8 said:
Faults like this are very difficult to diagnose, metering wiring for continuity is not the best way but is easier than volt dropping wiring under load which is the correct way. Also all earths need to be checked and cleaned , these days a lot of cars rely on the thread of the bolt for contact as paint is still present under terminals.
Using a scope at the relevant end of the wiring, be it ecu or actuator is the best way to find anomalies. As it will show a full trace and any glitches become more apparent.A simple text display of the voltage in such cases is useless. And all the better if you can view or log several channels at a time.
I'd assume the ecu can do this with some logging or graphing software too ? Not sure how fast it's resolution would be though.
But any wiring or electrical gremlin is the biggest pain in the hole ever to try and resolve.
FIXED!!!!!!!!!
Thanks to everyone that helped along the way. Monkfish, Blair at dynotorque, Eden Vauxhall and especially Paul at wortec who was eventually the man to fix it. After about a year and a half of problems I finally have a working ute! After Blair and Monkfish ran out of ideas I was a little worried to say the least!
To my limited knowledge I will best describe what the cause was to help others out with similar issues.
Here are the findings paul made:
We have checked the voltage drops across the pedal and throttle body circuits and set up data logging for these circuits, looking at voltage and resistance.
It looks like we have found an event just before the car fails where the voltage on circuit A increases and circuit B does not follow. This error is above the 4% allowed by the PCM so it puts the car in limp home mode.
So it it looks like the problem is from the throttle body to the PCM and not the pedal to PCM.
Paul later on discovered that is was caused by a magnetic field. The cable from the throttle body was being affected by the magnetic field being created by the fan coming on. To fix the problem a section of cable from the throttle body to the pcm was cut out and replaced with new cable which had better resistance better magnetic shielding. The voltage in this cable is now a lot further away from the failure point and the problem has FINALLY been fixed.
Please correct me paul if I have made a mistake.
Thanks again everyone,
One very happy owner! (fingers crossed this curse doesn't return)
Thanks to everyone that helped along the way. Monkfish, Blair at dynotorque, Eden Vauxhall and especially Paul at wortec who was eventually the man to fix it. After about a year and a half of problems I finally have a working ute! After Blair and Monkfish ran out of ideas I was a little worried to say the least!
To my limited knowledge I will best describe what the cause was to help others out with similar issues.
Here are the findings paul made:
We have checked the voltage drops across the pedal and throttle body circuits and set up data logging for these circuits, looking at voltage and resistance.
It looks like we have found an event just before the car fails where the voltage on circuit A increases and circuit B does not follow. This error is above the 4% allowed by the PCM so it puts the car in limp home mode.
So it it looks like the problem is from the throttle body to the PCM and not the pedal to PCM.
Paul later on discovered that is was caused by a magnetic field. The cable from the throttle body was being affected by the magnetic field being created by the fan coming on. To fix the problem a section of cable from the throttle body to the pcm was cut out and replaced with new cable which had better resistance better magnetic shielding. The voltage in this cable is now a lot further away from the failure point and the problem has FINALLY been fixed.
Please correct me paul if I have made a mistake.
Thanks again everyone,
One very happy owner! (fingers crossed this curse doesn't return)
I agree, nice diagnostics!
I work on ATE's for switched mode power supply production and problems like this can be a nightmare to sort out. The slightest problem with an earth or increased resistance in a connection somewhere will cause all sorts of problems and side effects that often seem completely unrelated to the original problem.
There are too many computers in cars now days. I'm glad that my '04 Monaro has a analogue, mechanical cable-activated throttle
I work on ATE's for switched mode power supply production and problems like this can be a nightmare to sort out. The slightest problem with an earth or increased resistance in a connection somewhere will cause all sorts of problems and side effects that often seem completely unrelated to the original problem.
There are too many computers in cars now days. I'm glad that my '04 Monaro has a analogue, mechanical cable-activated throttle
Digging up an old thread...
Anyone else having this issues? My 06 Monaro has done this 3 times, once when I picked it up after about 30min as I was taking a windy corner. Switched it off for a while, back on and no further problems on the freeway all the way home for ~2.5hrs.
Then a few drives later whilst idling in the driveway about to reverse in the garage. Parked it in limp mode
Finally, again today as I pulled up at the lights, pulled into a side street and switched it off for a while. Started again and all ok next 10min home.
Car wasn’t driven much in the last 12months so I’m wandering if condensation in the wiring to the throttle body is causing this.
Thoughts?
Anyone else having this issues? My 06 Monaro has done this 3 times, once when I picked it up after about 30min as I was taking a windy corner. Switched it off for a while, back on and no further problems on the freeway all the way home for ~2.5hrs.
Then a few drives later whilst idling in the driveway about to reverse in the garage. Parked it in limp mode
Finally, again today as I pulled up at the lights, pulled into a side street and switched it off for a while. Started again and all ok next 10min home.
Car wasn’t driven much in the last 12months so I’m wandering if condensation in the wiring to the throttle body is causing this.
Thoughts?
Yes I'm having same problems Monaro 6.0 Sunday morning 1.5 hours driving no problem drove home later on after about 20 mins cruising at 70 check engine/reduced power lights on and limp home mode, parked up switched off few mins restarted fine drove home ok.
This seems to be happening on mostly every drive now but always clears after switch off, there's no fault codes stored plus I sometimes get service vehicle soon light also.
My plan is to plug in my reader whilst it's in limp home when it next happens so see what happens at the weekend.........
This seems to be happening on mostly every drive now but always clears after switch off, there's no fault codes stored plus I sometimes get service vehicle soon light also.
My plan is to plug in my reader whilst it's in limp home when it next happens so see what happens at the weekend.........
jelevents, you're pretty close to me and mine's not being driven at the moment, if it becomes a consistent / regular enough problem you could try swapping my throttle body on to yours and see if it goes away? Just to eliminate that as a possible cause 
Would only take about 15 minutes to swap them over
Would only take about 15 minutes to swap them over
SturdyHSV said:
jelevents, you're pretty close to me and mine's not being driven at the moment, if it becomes a consistent / regular enough problem you could try swapping my throttle body on to yours and see if it goes away? Just to eliminate that as a possible cause
Would only take about 15 minutes to swap them over
Nice one James, will let you know how the weekend goes, it seems to be almost every drive now. 😔Would only take about 15 minutes to swap them over
jelevents said:
SturdyHSV said:
jelevents, you're pretty close to me and mine's not being driven at the moment, if it becomes a consistent / regular enough problem you could try swapping my throttle body on to yours and see if it goes away? Just to eliminate that as a possible cause
Would only take about 15 minutes to swap them over
Nice one James, will let you know how the weekend goes, it seems to be almost every drive now. ??Would only take about 15 minutes to swap them over
jelevents said:
Nope just a weekend drive, will let you know if any progress.
Any luck? I can across this GM technical bulletin that talks about moisture causing this. I’m going to check out when I get back and assume it’s written for LHD cars, so kick panel to check is on the RH side.
RipGMH said:
jelevents said:
Nope just a weekend drive, will let you know if any progress.
Any luck? I can across this GM technical bulletin that talks about moisture causing this. I’m going to check out when I get back and assume it’s written for LHD cars, so kick panel to check is on the RH side.Been ok last 10 years I've asked him for some more info he's gonna update with some pictures.
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