Heater Support Pump and Voltage error woes
- Thread starter T6_FunBus
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- heater support pump
One other thing, if someone could next time they are plugged into their van, please check these circuit activations it would be appreciated.
As I mention, the heater support pump secondary circuit on mine is almost always 95%, with ignition on / engine off, engine on cold or warm, and after engine turn off until it switches off and ecu goes to sleep.
The other two seem to vary % depending on how hot the engine is, running time and load. They also switch off when ECU goes to sleep.
If someone could also check reference voltage with ignition on, van / alternator running against battery voltage it would be appreciated to see if mine is within spec.
Cheers.
As I mention, the heater support pump secondary circuit on mine is almost always 95%, with ignition on / engine off, engine on cold or warm, and after engine turn off until it switches off and ecu goes to sleep.
The other two seem to vary % depending on how hot the engine is, running time and load. They also switch off when ECU goes to sleep.
If someone could also check reference voltage with ignition on, van / alternator running against battery voltage it would be appreciated to see if mine is within spec.
Cheers.
Typically yes. However, on hot day (+25 °C) having just ignition on before engine start can also be seen at 10% (=OFF)
Yes, agreed.
You mean sensor reference voltage? 5.000 Volts - would expect to be the same always. However, never verified engine running.
Also the ECU end can be somewhat verified by unplugging a sensor and using VCDS, e.g. below charge air cooler output sensor unplugged --> thus temperature -40 °C
IDE04003 Charge air temperature sensor B1S1/B1S2:18/-40 °C
IDE07710 Charge air cooler output: temp. sensor 1: B1: raw value -40.0 °C
IDE07711 Charge air cooler output: temp. sensor 1: B1: raw voltage 4.999 V
Note: above unplugging will trigger fault: 23792 - Intercooler Temperature Sensor (Bank 2) - P00A3 00 [163] - Short to Plus
Thanks, ref the reference voltage. This is under 01 engine, reads 11ish volts when battery is 12+. When alternator is running and over 13v, reference voltage shows 12.
Raw sensor voltage is normally in the 3’s from what I remember from the random ones I selected but I’ll need to go back through some screen caps to double check.
Had a couple of hours today to do some trouble shooting on this. Documenting it here for future reference while I remember.
Jacked the van up and got underneath.
Egr coolant pump tested with volt meter
Solid 12v on 12v wire
Green - yellow Signal wire 2.9v solid
Tried new power and ground wire but with original control wire
Resulted in the same error - heater support pump supply voltage
Removed control wire - new error - EGR cooler pump control circuit open
Remove 12v wire - egr cooler pump control circuit low
All the time heater support pump supply voltage error comes back.
Charge air cooler pump
Suspect 12v - but difficult probing it
Signal wire 2.9v solid
Tried new 12v and ground with existing ecu wire
Same error - heater support pump supply voltage
Remove control wire - charge air cooler control circuit open
Remove 12v wire - charge air cooler pump control circuit low
Heater support pump
Suspect control wire (already attempted to replace)
Tried new 12v and ground same error
12v seems solid
Signal wire from ecu at only at 1.2v max
Removed control wire - no circuit open error like on other pump.
Heater support pump supply voltage error returns.
Also have permanent reference voltage open circuit now
EGR pump disconnected completely, shows open circuit on EGR pump, heater support pump error eventually comes back too, hence think this pump is OK, as it doesn’t show this error right away. If this pump was faulty and throwing heater support pump supple voltage error then error would not come back when ecu is disconnected from it as it can’t see this pump.
With both egr and charge cooler pump plug disconnected, I get both control circuit open errors on them specifically.
Eventually still get heater support pump supply voltage error even with the two front pumps disconnected.
CONNECTED control wire of heater support pump to Charge Air Cooler pump with charge air cooler pump having fresh 12v and ground feeds. But with charge air cooler and egr pump disconnected. STILL got HEATER SUPPORT PUMP SUPPLY VOLTAGE error, so this rules out the Heater Support Pump being faulty on arrival, as I get the same error when the ECU is connected to an identical part no elsewhere on the engine.
With control wire disconnected from Heater Support Pump - no control circuit error like others. Can clear any error and none show, then eventually the heater support pump supply voltage error comes back exactly as it does even with pump connected.
Suspect replacement ecu control wire is bad, also suspect reference voltage circuit open is due to sensor reference voltage being lower than expected (1-1.2v rather than 3v).
Maybe the wire I fitted was already damaged but not visible (it was an old spool of wire).
So after all that testing I think it says:
- All three pumps OK and not faulty
- Power and ground to all pumps OK
- Control wire to EGR and Charge cooler pumps OK
- All three pumps report different errors when disconnected, so supply voltage error seems to be specific to heater pump
- Suspect new wire to Heater is badly connected ECU end or has a break / damage that I was unaware of when fitting
What I really need to do is get to the ecu, power it up and test the signal wire from the ecu connector at that end, if it’s 2.9-3ish volts that end then the new wire is trash. If it’s low at the ecu connector end, then maybe a bad pin / connection in the block.
If all that is checked and / or replaced and turns out OK, and another new wire fitted, and signal voltage still low and error remains, then I cannot see it being anything else other than ECU.
It’s going to be a pain, as I need to remove battery etc, get to ecu connector, then connect the battery and power up the ecu with the battery outside the van… it’s the only way I can test the control wire at source. The only way I can think of doing that is to use clamps and leads to the battery outside the van on a table…
It’s going to be a while before I get the weather or any time to test this, but that’s the next plan of attack, so time to strip it all out and look at the control wire / ecu again.
Jacked the van up and got underneath.
Egr coolant pump tested with volt meter
Solid 12v on 12v wire
Green - yellow Signal wire 2.9v solid
Tried new power and ground wire but with original control wire
Resulted in the same error - heater support pump supply voltage
Removed control wire - new error - EGR cooler pump control circuit open
Remove 12v wire - egr cooler pump control circuit low
All the time heater support pump supply voltage error comes back.
Charge air cooler pump
Suspect 12v - but difficult probing it
Signal wire 2.9v solid
Tried new 12v and ground with existing ecu wire
Same error - heater support pump supply voltage
Remove control wire - charge air cooler control circuit open
Remove 12v wire - charge air cooler pump control circuit low
Heater support pump
Suspect control wire (already attempted to replace)
Tried new 12v and ground same error
12v seems solid
Signal wire from ecu at only at 1.2v max
Removed control wire - no circuit open error like on other pump.
Heater support pump supply voltage error returns.
Also have permanent reference voltage open circuit now
EGR pump disconnected completely, shows open circuit on EGR pump, heater support pump error eventually comes back too, hence think this pump is OK, as it doesn’t show this error right away. If this pump was faulty and throwing heater support pump supple voltage error then error would not come back when ecu is disconnected from it as it can’t see this pump.
With both egr and charge cooler pump plug disconnected, I get both control circuit open errors on them specifically.
Eventually still get heater support pump supply voltage error even with the two front pumps disconnected.
CONNECTED control wire of heater support pump to Charge Air Cooler pump with charge air cooler pump having fresh 12v and ground feeds. But with charge air cooler and egr pump disconnected. STILL got HEATER SUPPORT PUMP SUPPLY VOLTAGE error, so this rules out the Heater Support Pump being faulty on arrival, as I get the same error when the ECU is connected to an identical part no elsewhere on the engine.
With control wire disconnected from Heater Support Pump - no control circuit error like others. Can clear any error and none show, then eventually the heater support pump supply voltage error comes back exactly as it does even with pump connected.
Suspect replacement ecu control wire is bad, also suspect reference voltage circuit open is due to sensor reference voltage being lower than expected (1-1.2v rather than 3v).
Maybe the wire I fitted was already damaged but not visible (it was an old spool of wire).
So after all that testing I think it says:
- All three pumps OK and not faulty
- Power and ground to all pumps OK
- Control wire to EGR and Charge cooler pumps OK
- All three pumps report different errors when disconnected, so supply voltage error seems to be specific to heater pump
- Suspect new wire to Heater is badly connected ECU end or has a break / damage that I was unaware of when fitting
What I really need to do is get to the ecu, power it up and test the signal wire from the ecu connector at that end, if it’s 2.9-3ish volts that end then the new wire is trash. If it’s low at the ecu connector end, then maybe a bad pin / connection in the block.
If all that is checked and / or replaced and turns out OK, and another new wire fitted, and signal voltage still low and error remains, then I cannot see it being anything else other than ECU.
It’s going to be a pain, as I need to remove battery etc, get to ecu connector, then connect the battery and power up the ecu with the battery outside the van… it’s the only way I can test the control wire at source. The only way I can think of doing that is to use clamps and leads to the battery outside the van on a table…
It’s going to be a while before I get the weather or any time to test this, but that’s the next plan of attack, so time to strip it all out and look at the control wire / ecu again.
Just went back through some old messages, and it seems that control wire on the heater pump was previously fluctuating voltage when connected, I tested it NOT connected direct from the plug) as I did with the other pumps).
I am not sure whether the all three control wires should show around 3v at rest from ecu wire when not connected to the pump. But if they should, then again points to the ecu wire being suspect.
I still find it weird there is no open circuit error on this pump like the other two when control wire disconnected. Seems the only error I get when it is or isn’t connected is the ‘heater support pump supply voltage’. And again, I know the supply voltage is fine from the 12v supply, so I cannot see how it can refer to anything else other than the ecu wire?????
I am not sure whether the all three control wires should show around 3v at rest from ecu wire when not connected to the pump. But if they should, then again points to the ecu wire being suspect.
I still find it weird there is no open circuit error on this pump like the other two when control wire disconnected. Seems the only error I get when it is or isn’t connected is the ‘heater support pump supply voltage’. And again, I know the supply voltage is fine from the 12v supply, so I cannot see how it can refer to anything else other than the ecu wire?????
Spent another 5 hours on the van today - still no joy.
Dug out the ECU, replaced ecu signal wire again - same error.
Got to ecu again, removed the signal wire and pin from ecu, tested pin and wire continuity - all good. Replaced pin and ecu wire, tried another new signal wire, with new power wire from sb29 and fresh ground and fresh plug - same error.
I seem to have a permanent 00538-011 - reference voltage open circuit, it’s been like this for a while now along with heater support pump supply voltage error.
Checked ground wire and pin to ecu - looked ok. Removed all ground connectors in ebook and cleaned and replaced.
Checked all fuses in engine fuse box -all ok.
Removed again refitted and put back to normal, got it all back together and forgot the plastic ecu connector cover, so had to remove all again and start over and replace.
That’s another 5 hours of my life I’m getting back.
Reference voltage measuring about 9v now, but I didn’t start the van.
Out of ideas now.
Dug out the ECU, replaced ecu signal wire again - same error.
Got to ecu again, removed the signal wire and pin from ecu, tested pin and wire continuity - all good. Replaced pin and ecu wire, tried another new signal wire, with new power wire from sb29 and fresh ground and fresh plug - same error.
I seem to have a permanent 00538-011 - reference voltage open circuit, it’s been like this for a while now along with heater support pump supply voltage error.
Checked ground wire and pin to ecu - looked ok. Removed all ground connectors in ebook and cleaned and replaced.
Checked all fuses in engine fuse box -all ok.
Removed again refitted and put back to normal, got it all back together and forgot the plastic ecu connector cover, so had to remove all again and start over and replace.
That’s another 5 hours of my life I’m getting back.
Reference voltage measuring about 9v now, but I didn’t start the van.
Out of ideas now.
Right, I got the van into a local VW specialist and they are also at a loss.
They came to the same conclusion as me, in that the pumps are all working, all functions and output tests work, and couldn’t find anything wrong…
They only charge me a couple of hours labour, but, they suggested coding out the DTC from the ECU. They said I could replace the ecu at great expense and still get the same error.
All I can think of now is perhaps going that route and just getting the DTC removed from the van, since the pumps are working as expected?…
They came to the same conclusion as me, in that the pumps are all working, all functions and output tests work, and couldn’t find anything wrong…
They only charge me a couple of hours labour, but, they suggested coding out the DTC from the ECU. They said I could replace the ecu at great expense and still get the same error.
All I can think of now is perhaps going that route and just getting the DTC removed from the van, since the pumps are working as expected?…
Jacksoncrew
New Member
Hey mate have you had any success with this yet? I’ve had this fault for a while and only just replaced the punt and still have this issue would love to know if you’ve fixed it
Nope still have it, I’ve given up trying to fix it and just waiting to get the van in to have the DTC mapped out / disabled.
I’ve pretty much tried everything, from replacing pump, new control, positive and ground wires, ecu pins / connectors, trying other pumps, etc etc.
Output tests work, the pump works and shuts off as expected, and live data shows it working correctly. All the other pumps are also fine and working correctly. My local VW specialist is also at a loss and it was their suggestion to just remove the DTC. I’ve been using the van for 6 months will zero ill effects, everything else works stop start etc, but I get the error and an EML after three restarts meaning an MOT failure. Even though there is no limp mode, and everything still functions.
It’s the dumbest problem ever, and I’ve got sick of stressing about it, since it’s not affecting use of the van at all. So I have just ignored it now and used the van as normal, at some point will find a place to map out the DTC.
I’ve pretty much tried everything, from replacing pump, new control, positive and ground wires, ecu pins / connectors, trying other pumps, etc etc.
Output tests work, the pump works and shuts off as expected, and live data shows it working correctly. All the other pumps are also fine and working correctly. My local VW specialist is also at a loss and it was their suggestion to just remove the DTC. I’ve been using the van for 6 months will zero ill effects, everything else works stop start etc, but I get the error and an EML after three restarts meaning an MOT failure. Even though there is no limp mode, and everything still functions.
It’s the dumbest problem ever, and I’ve got sick of stressing about it, since it’s not affecting use of the van at all. So I have just ignored it now and used the van as normal, at some point will find a place to map out the DTC.
Last edited:
Just realised I never did update on this.
On my almost never ending journey, I discovered and talked to other people who had the same issue with these shocking designed pumps that seem to plague the vw (and Mercedes) range.
I went through it with another garage and a lead vw and Mercedes tech that worked there, and spent another £700 for the privilege of it (although, to be fair this did include a years ticket, and a new engine mount as they spotted the old one a bit worn).
I went through all the checks and things I had done.
The conclusion was that a voltage error seems to point to a short in the circuit, where the ECU sees a different voltage on the signal wire than expected. Apparently it is fairly common for these pumps to short out internally, as the electrics are not well seperated, and water can leak into the internal electrics and cause random short errors. This makes sense, as we went through my history of saved logs, and initially there was a momentary short to b+ and to ground on the pump before my problems started.
When the pump internally leaks water into the electrical part, the shorting can fire voltage back down the signal wire that is not expected. The ecu then throws such errors (note this can also occur if the wires are not installed properly following work such as clutch / flywheel. Note also, in my case first garage to replace the pump did notice wire to heater pump was strained, rubbing and not rerouted correctly by the original garage that did the clutch / flywheel).
In any case, we tried another new pump, at all locations, and my bypass loom at all locations. The same error persisted.
After further tests and data logging, all pumps are working as expected. This puzzled even the techs, they still thought it highly unlikely that an internal ecu error could occur or that the ecu was at fault. They had only seen one ECU failure in all the issues they have had with these pump circuits.
The end result was, another pump as front EGR cooler sounded ‘weak’, and tested all signal wires / scoped, proved to be OK. So they updated software and coded out the specific error from the ECU. ECU will still report other shorts should the circuit fail (short to ground, b+ etc), just not supply voltage problem that seems to be stuck. The van works perfectly fine and has done even with this error since last November!
The other option on the table was a new ECU as well, but even though everything was working (also no water ingress or damage to ecu on inspection). They still believed replacing ecu was not worth it.
Bottom line, the pumps are working, circuits are fine, ECU otherwise seems fine and the error is gone.
Good luck to anyone else troubleshooting the same error in the future. I spent over £1000 on this and countless weekends and evenings!
On my almost never ending journey, I discovered and talked to other people who had the same issue with these shocking designed pumps that seem to plague the vw (and Mercedes) range.
I went through it with another garage and a lead vw and Mercedes tech that worked there, and spent another £700 for the privilege of it (although, to be fair this did include a years ticket, and a new engine mount as they spotted the old one a bit worn).
I went through all the checks and things I had done.
The conclusion was that a voltage error seems to point to a short in the circuit, where the ECU sees a different voltage on the signal wire than expected. Apparently it is fairly common for these pumps to short out internally, as the electrics are not well seperated, and water can leak into the internal electrics and cause random short errors. This makes sense, as we went through my history of saved logs, and initially there was a momentary short to b+ and to ground on the pump before my problems started.
When the pump internally leaks water into the electrical part, the shorting can fire voltage back down the signal wire that is not expected. The ecu then throws such errors (note this can also occur if the wires are not installed properly following work such as clutch / flywheel. Note also, in my case first garage to replace the pump did notice wire to heater pump was strained, rubbing and not rerouted correctly by the original garage that did the clutch / flywheel).
In any case, we tried another new pump, at all locations, and my bypass loom at all locations. The same error persisted.
After further tests and data logging, all pumps are working as expected. This puzzled even the techs, they still thought it highly unlikely that an internal ecu error could occur or that the ecu was at fault. They had only seen one ECU failure in all the issues they have had with these pump circuits.
The end result was, another pump as front EGR cooler sounded ‘weak’, and tested all signal wires / scoped, proved to be OK. So they updated software and coded out the specific error from the ECU. ECU will still report other shorts should the circuit fail (short to ground, b+ etc), just not supply voltage problem that seems to be stuck. The van works perfectly fine and has done even with this error since last November!
The other option on the table was a new ECU as well, but even though everything was working (also no water ingress or damage to ecu on inspection). They still believed replacing ecu was not worth it.
Bottom line, the pumps are working, circuits are fine, ECU otherwise seems fine and the error is gone.
Good luck to anyone else troubleshooting the same error in the future. I spent over £1000 on this and countless weekends and evenings!
Peter Rhymes
Member
Hi Guys ,I have forgotten how to start a new chat. I am hoping that someone involved this chat could help. My T6 is throwing up an EML on the dash. My code reader says 27166 . If I reset the code the EML comes back on after about 15 miles. Also I’m not sure if the Alternator is working correctly ? Some times it kicks out 15 volts other times only 12.5 volts. Could this be linked to the other fault code ? I never get the not charging light on the dash. Thanks for any feed back. Cheers, Pete.
Carista perhaps? Any other clues?
T6/T6.1 has a "smart" alternator. Puts out 15 Volts under engine braking, and during DPF regeneration.
f you have T6 with Climatic A/C (the one with 4-speed cabin blower) switch it to speed 2 (or higher) - to force alternator act more traditionally - no more charging below 13.4 Volts.
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