I have searched the Internet but haven't found any consistent information on this, is Group #4 the correct location for checking battery and/or charging system voltage through the VCDS?
VW MKIV - Battery/Charging System Voltage, Which Group?
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Impossible to provide an authoritative answer without knowing what ECU this car has.
FWIW, Terminal 30 voltage reported via any control module will always be somewhat lower than the actual battery voltage due to resistivity voltage drops in the wiring, fuses, relays and so on that are between the battery and the control module.
-Uwe-
FWIW, Terminal 30 voltage reported via any control module will always be somewhat lower than the actual battery voltage due to resistivity voltage drops in the wiring, fuses, relays and so on that are between the battery and the control module.
-Uwe-
Okay thank you for that additional info. regarding the expectation of a lower reading via VCDS as compared to the measurement gathered at the battery, however, is it normal for that difference to be as great as 1.5 - 2.0 volts?
The ECU is an AWP #06A 906 032LS, this ECU is a proper upgrade in a 2000 Beetle GLX M/T stage 3+ setup, this setup has been in place for several years with no issue.
The ECU is an AWP #06A 906 032LS, this ECU is a proper upgrade in a 2000 Beetle GLX M/T stage 3+ setup, this setup has been in place for several years with no issue.
Then Group 004, field 2 will be your "battery voltage".
1.5 - 2.0 volts strikes me as somewhat high. How steady is it, or how much does it fluctuate? Dodgy connections will often vary in resistance.
-Uwe-
1.5 - 2.0 volts strikes me as somewhat high. How steady is it, or how much does it fluctuate? Dodgy connections will often vary in resistance.
-Uwe-
Great, thank you.
So, some additional information on my inquiry:
Recently I began seeing an "occasional" Airbag light come on briefly then turn off, this is of course accompanied by fault code #00532.
At first I thought I might be dealing with a failed Clockspring which is still a possibility, but, watching Group #4 (which is the only place I found voltage) while turning the steering wheel, the voltage reading did not change so I kind of ruled a failed Clockspring out for now.
Whenever the problem occurs, my Autometer Wideband A/F gauge begins reading rich, as low as 0.69 Lambda at idle and as low as 0.90 Lambda with some surging during highway cruising, the power windows drag slowly and the dash lights sometimes dim or flicker, on one occasion the cluster gauges went to their off resting point then resumed normal operation seconds later, when it resumes normal operation the A/F reading at idle and cruising goes back to 1.00 Lambda or centering close to stoichiometric and all else returns to normal.
I noticed that the voltage reading on the scan tool (as Uwe mentioned) was considerably lower than the reading obtained from the alternator or battery, this made me think that "if" the comparative difference between the two readings are at somewhat of a parallel, if the alternator (at operating temperature) drops it's output below the norm, then the already lower in-car voltage might drop low enough to cause the issues that I am experiencing.
Just a thought...
With the engine running, I have checked voltage across the battery terminals, at the alternator output and at both sides of all metal fuses in the fuse box on top of the battery, the readings are all the same.
I have also checked accuracy of my in car Autometer voltage gauge against the under hood readings I got using a Fluke digital volt meter, the results were identical, so I know my in car volt gauge is accurate.
Just not totally sure how voltage/current is fed inside the cockpit as appose to outside of it, or what the minimum voltage reading should be when measuring via scan tool.
So, some additional information on my inquiry:
Recently I began seeing an "occasional" Airbag light come on briefly then turn off, this is of course accompanied by fault code #00532.
At first I thought I might be dealing with a failed Clockspring which is still a possibility, but, watching Group #4 (which is the only place I found voltage) while turning the steering wheel, the voltage reading did not change so I kind of ruled a failed Clockspring out for now.
Whenever the problem occurs, my Autometer Wideband A/F gauge begins reading rich, as low as 0.69 Lambda at idle and as low as 0.90 Lambda with some surging during highway cruising, the power windows drag slowly and the dash lights sometimes dim or flicker, on one occasion the cluster gauges went to their off resting point then resumed normal operation seconds later, when it resumes normal operation the A/F reading at idle and cruising goes back to 1.00 Lambda or centering close to stoichiometric and all else returns to normal.
I noticed that the voltage reading on the scan tool (as Uwe mentioned) was considerably lower than the reading obtained from the alternator or battery, this made me think that "if" the comparative difference between the two readings are at somewhat of a parallel, if the alternator (at operating temperature) drops it's output below the norm, then the already lower in-car voltage might drop low enough to cause the issues that I am experiencing.
Just a thought...
With the engine running, I have checked voltage across the battery terminals, at the alternator output and at both sides of all metal fuses in the fuse box on top of the battery, the readings are all the same.
I have also checked accuracy of my in car Autometer voltage gauge against the under hood readings I got using a Fluke digital volt meter, the results were identical, so I know my in car volt gauge is accurate.
Just not totally sure how voltage/current is fed inside the cockpit as appose to outside of it, or what the minimum voltage reading should be when measuring via scan tool.
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When you say it seems high, do you mean the amount of voltage or are you referring to a large variance between the scan tool reading and the battery/alternator reading?
The reading from the scan tool does fluctuate quite a bit in my opinion at times, I’ve seen it go from the high elevens to 13 volts on acassion.
In actuality, I’ve seen up to a volt difference between the scan tool reading and that of the Fluke measurement at the alternator, this at engine operating temperature with no accessories on.
With the engine cold, the output at both points is much higher, usually in the area of 14 volts with maybe a 0.25 to a 0.5 volt difference between the scan tool and the alternator/battery reading.
By the way, the car has a fairly new Odyssey Extreme PC1200 battery which I keep maintained with Odyssey’s best charger.
The alternator is a Direct fit DC Power Engineering SPX320 (320 amp. hot rated), I’m wondering if it is failing somehow and causing these issues...
The reading from the scan tool does fluctuate quite a bit in my opinion at times, I’ve seen it go from the high elevens to 13 volts on acassion.
In actuality, I’ve seen up to a volt difference between the scan tool reading and that of the Fluke measurement at the alternator, this at engine operating temperature with no accessories on.
With the engine cold, the output at both points is much higher, usually in the area of 14 volts with maybe a 0.25 to a 0.5 volt difference between the scan tool and the alternator/battery reading.
By the way, the car has a fairly new Odyssey Extreme PC1200 battery which I keep maintained with Odyssey’s best charger.
The alternator is a Direct fit DC Power Engineering SPX320 (320 amp. hot rated), I’m wondering if it is failing somehow and causing these issues...
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A drop of 1.5-2.0 volts suggests a large resistance between the battery and the measuring point, so it's that difference in voltage which is too high.
This suggests a faulty connection somewhere between the two points, possibly due to a loose or corroded connection, and from what you say a connection that becomes higher resistance when the engine is warmed up which IMHO points more towards a loose connection.
Thank you for your input PetrolDave.
You may have missed it but in my last post, I did amend my initial measurement of a 1.5 - 2.0 volts disparity between the alternator voltage output and that being registered on the scan tool, after a recheck, that number was changed to at most, a 1-volt variance.
Taking into consideration what Uwe stated in his first post coupled with the amended measurement of a “maximum” 1-volt variance, is that still too much of a disparity?
Note: All charging system connections have been check and they are clean and rock solid.
I have read numerous Airbag light/00532 fault stories where people were having similar experiences as myself, in many of those stories a failing alternator ended up being the culprit, this is partly why I am considering this as a possibility.
You may have missed it but in my last post, I did amend my initial measurement of a 1.5 - 2.0 volts disparity between the alternator voltage output and that being registered on the scan tool, after a recheck, that number was changed to at most, a 1-volt variance.
Taking into consideration what Uwe stated in his first post coupled with the amended measurement of a “maximum” 1-volt variance, is that still too much of a disparity?
Note: All charging system connections have been check and they are clean and rock solid.
I have read numerous Airbag light/00532 fault stories where people were having similar experiences as myself, in many of those stories a failing alternator ended up being the culprit, this is partly why I am considering this as a possibility.
I concur.
But one thing that people often forget: That high resistance or dodgy connection can be on the negative (ground) side of the circuit just as easily as on the positive side.
-Uwe-
Well, I removed the performance alternator and sent it to the manufacturer for evaluation/repair, I’ll wait to see what they find if anything.
In the meantime, I reinstalled the original factory VW alternator and so far, it is operating much better than the performance unit, voltage is staying at or close to 14+ volts even at operating temps. With loads.
Time will tell if that was the problem.
In the meantime, I reinstalled the original factory VW alternator and so far, it is operating much better than the performance unit, voltage is staying at or close to 14+ volts even at operating temps. With loads.
Time will tell if that was the problem.
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The alternator suspected of issues, no, it is not a factory VW part, however, the company uses all OES and/or OES grade parts (NO Chinese parts) in their alternators and mine has been in service for about five years, it endured a failed radiator which before being replace sprayed coolant on it over a period of time several months ago, being dowsed with coolant may have played a part in it’s apparent demise.
Up until recently, the DC Power alternator worked flawlessly, holding at a rock solid 13.5 - 14 volts while “idling” with the A/C, stereo, headlights and driving lights etc. on, something the stock VW alternator will not come close to tolerating.
In regards to the original subject matter of this thread, as of late I have considered that I might be dealing with multiple problems simultaneously.
1. A failing alternator causing the Illumination of the airbag light/related fault code along with the dash lights cluster gauges flickering at times.
2. “Possible” failing MAF Sensor, Map Sensor etc. causing the random engine rich condition, rough idle and surging or light jerking at speed.
We’ll see...
Up until recently, the DC Power alternator worked flawlessly, holding at a rock solid 13.5 - 14 volts while “idling” with the A/C, stereo, headlights and driving lights etc. on, something the stock VW alternator will not come close to tolerating.
In regards to the original subject matter of this thread, as of late I have considered that I might be dealing with multiple problems simultaneously.
1. A failing alternator causing the Illumination of the airbag light/related fault code along with the dash lights cluster gauges flickering at times.
2. “Possible” failing MAF Sensor, Map Sensor etc. causing the random engine rich condition, rough idle and surging or light jerking at speed.
We’ll see...
Time for an update:
Although I believe my high output alternator at least has an issue of reduced output when hot, installing the factory unit did not correct the intermittent and random on/off airbag light and related 00532 fault code, it also did not correct the random "rich" fuel issue or cluster gauge needle swings.
Looking at the reduced performance and symptoms displayed when the the system would go rich, I decided to replace the MAF sensor on Thursday of last week and reset the ECU.
It has been about a week now with no airbag light, no fault code(s), and no weird cluster gauge activity, it would appear that the MAF sensor was intermittently shorting or failing in a way that was causing some sort of feedback into the system creating the problems mentioned.
Although I believe my high output alternator at least has an issue of reduced output when hot, installing the factory unit did not correct the intermittent and random on/off airbag light and related 00532 fault code, it also did not correct the random "rich" fuel issue or cluster gauge needle swings.
Looking at the reduced performance and symptoms displayed when the the system would go rich, I decided to replace the MAF sensor on Thursday of last week and reset the ECU.
It has been about a week now with no airbag light, no fault code(s), and no weird cluster gauge activity, it would appear that the MAF sensor was intermittently shorting or failing in a way that was causing some sort of feedback into the system creating the problems mentioned.
Well folks, it has now been over 3 weeks since I replaced the MAF sensor, still no fault codes.
last checked today, Short term fuel trim is 3.2 / Long term fuel trim is -3.9, so far all is great in the neighborhood.
It would appear that the old MAF sensor had some real issues, never seen one fail and cause such strange anomalies.
last checked today, Short term fuel trim is 3.2 / Long term fuel trim is -3.9, so far all is great in the neighborhood.
It would appear that the old MAF sensor had some real issues, never seen one fail and cause such strange anomalies.
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