Heater Support Pump and Voltage error woes

[T6_FunBus]

Here is the ECU pin layout. You want the (smaller) left 60 pin plug, pin 43. On the diagram, it's 3rd pin from the right, second row from the top. From that, you should be able to work out which pin it is.

The plug does come apart, they're just fiddly.

View attachment 229564

Thanks Craig, yes that was the one, removed small connector, pin 43, 3rd one in was blue and purple, it ‘looked’ ok. I cut it about three inches back from ecu block - I didn’t want to leave the old remnants of the original wire connected in case it was broken somewhere under engine where I couldn’t see and shorted something out still sending a bad signal to ecu.

I couldn’t get the plug apart tbh, pulled out the locking tab and the top and bottom plastic connector would not move, I didn’t want to force it and risk breaking it, the plastic on the top cover that slides off was brittle enough and a small bit of plastic flung off when I was sliding it off.

The end of the ECU connector was good, no green or any corrosion, some wet around the outside plastic, non inside - pins and inside connector all dry.

I did notice someone had previously added a wire to 6 and 8, appears to be ecu ground and knock sensor. No clue why but it was an ex as van, so they may have used those two to feed into another unit. The ground had shielding on the white wire from the ecu block, then had another shielding over it and another wire coming out. If it was a bad ecu ground though I would think it would be taking a dump completly and not just this issue?

Thanks again for your support!

 

[Craig.]

Thanks Craig, it might be worth it? Although I already ran a new .5mm wire from the ecu (I cut then spliced the purple blue wire about three inches behind the ecu pin into the new wire, assuming the splice was good). I’ve already tried a new plug (it was just an generic vw 3 pin style connector jobbie with sliding grey tab, wires already attached, but fits fine) and then joined new power wire to fuse box, new ground to a bolt under the bonnet to chassis, and then that ecu wire to the three wires that came on the plug in the correct order, and got exactly the same result /shrugs.

I could try it all again with another loom, but not sure if it will just result in the same?

Just thinking if you can rule out the wiring to a point where it can no longer be suspect then you can focus your efforts elsewhere. No costs involved apart from a little more time on your end running the new loom.

 

[T6_FunBus]

Just thinking if you can rule out the wiring to a point where it can no longer be suspect then you can focus your efforts elsewhere. No costs involved apart from a little more time on your end running the new loom.

This is true. I assume a ground anywhere on a bolt in the engine bay is good enough? And a wire straight into fuse 29?

I just can’t see how the wires I ran from ground and even testing from battery were bad as I just put it over the top of the engine visible to test - no snags etc, they were twisted and crimped at the plug end - definitly making a positive mechanical connection.

I do know the static supply voltage error is present when the ECU wire is not connected, as I tested that too. If the ECU wire is removed, the pump runs with ignition on, but ECU reports same static fault.

I think if I had another pump to test that would be an idea, but no clue where to get one from to test, at least knowing one works and does not error without wasting £200 on a part from VW.

I’m not going to be able to get to it again to strip completely apart for a while, as I’ve spend the last two weekends on it and it’s not ideal to mess around with in the dark evening. But I might take you up on the offer of another loom thanks.

 

[Craig.]

This is true. I assume a ground anywhere on a bolt in the engine bay is good enough? And a wire straight into fuse 29?

I just can’t see how the wires I ran from ground and even testing from battery were bad as I just put it over the top of the engine visible to test - no snags etc, they were twisted and crimped at the plug end - definitly making a positive mechanical connection.

I do know the static supply voltage error is present when the ECU wire is not connected, as I tested that too. If the ECU wire is removed, the pump runs with ignition on, but ECU reports same static fault.

I think if I had another pump to test that would be an idea, but no clue where to get one from to test, at least knowing one works and does not error without wasting £200 on a part from VW.

I’m not going to be able to get to it again to strip completely apart for a while, as I’ve spend the last two weekends on it and it’s not ideal to mess around with in the dark evening. But I might take you up on the offer of another loom thanks.

Can you get the old pump back from the garage? Seeing as your fault is still present then logically that pump is likely not at fault.

A side note, I would get your power from a different fuse location too, and use a fresh fuse. Rule out as much as possible. Any good chassis earth will do but I'd earth to the same earth point by the ECU, seeing as you're running a wire to there anyway then it's no extra effort and it's a factory earth point so won't get better than that.

 

[T6_FunBus]

Can you get the old pump back from the garage? Seeing as your fault is still present then logically that pump is likely not at fault.

A side note, I would get your power from a different fuse location too, and use a fresh fuse. Rule out as much as possible. Any good chassis earth will do but I'd earth to the same earth point by the ECU, seeing as you're running a wire to there anyway then it's no extra effort and it's a factory earth point so won't get better than that.

I’ve just sent them a mail asking about that, although maybe they’ve binned it by now :/

I didn’t try a different earth, but I did try direct fused feed from battery terminal to rule out that feed from the fuse box and still same error.

 

[T6Bob32]

This appears to be the part they fitted 5Q0965561B, at least it looks like it from the last part of the part no I can see.

Transporter T6 2016-2019 Water Pump EGR System - 5Q0965561B

- Transporter T6 2016-2019 Water Pump EGR System - 5Q0965561B - Genuine VW Parts and Accessories

vwvanpartsdirect.co.uk

I'm by no means qualified or experienced enough to chip in here but ...

I think you've mentioned you've checked they changed the pump. Are you absolutely certain it was the right one?

I only ask because I almost changed the wrong one a few months ago. The EGR coolant pump and auxillary heater pump are the same. For me it was the other way round. Needed to change EGR coolant pump, but went for heater pump by accident.

 

[T6_FunBus]

I'm by no means qualified or experienced enough to chip in here but ...

I think you've mentioned you've checked they changed the pump. Are you absolutely certain it was the right one?

I only ask because I almost changed the wrong one a few months ago. The EGR coolant pump and auxillary heater pump are the same. For me it was the other way round. Needed to change EGR coolant pump, but went for heater pump by accident.

View attachment 229569

Thanks for the reply.

When troubleshooting I unplugged the other two and they said ‘open circuit’, one is EGR and one is charge cooler. The one at the back is definitely the heater support pump. In fact you just gave me an idea, if I unplug the connector all together it should show ‘open circuit’ if the ECU is communicating with the pump? Not sure what that proves, I mean at least it should show the ECU is connected to the connector going to the pump?

The weird thing is, thinking about it, before when I disconnected the ecu wire only, it still showed a static error for ‘supply voltage’, surely it should have said ‘open circuit’ hmmmm.

 

[T6_FunBus]

Hmmm, maybe that’s a red herring actually. Although I’d expect it to say open circuit like the other two, it seems not everything shows that when unplugged. As for example when I had a couple of other sensors unplugged on the intake pipe, it showed these and not open circuit, so maybe heater support pump isn’t guaranteed to error same in ecu as the other pumps?

 

[Craig.]

Hmmm, maybe that’s a red herring actually. Although I’d expect it to say open circuit like the other two, it seems not everything shows that when unplugged. As for example when I had a couple of other sensors unplugged on the intake pipe, it showed these and not open circuit, so maybe heater support pump isn’t guaranteed to error same in ecu as the other pumps?

View attachment 229570

View attachment 229571

It depends on how the circuit is monitored. Some will be by resistance, some will be by direct monitoring.

 

[T6Bob32]

I think if I had another pump to test that would be an idea, but no clue where to get one from to test, at least knowing one works and does not error without wasting £200 on a part from VW.

Auxiliary Coolant Water Pump For VW Golf VII Passat B8 Transporter T6 Polo VI CC | eBay

I know it's a bit gash but might be worth a punt on a £16.88 fleabay job for troubleshooting purposes?

There are many others available at varying levels of gashness

 

[T6_FunBus]

Auxiliary Coolant Water Pump For VW Golf VII Passat B8 Transporter T6 Polo VI CC | eBay

I know it's a bit gash but might be worth a punt on a £16.88 fleabay job for troubleshooting purposes?

There are many others available at varying levels of gashness

Not a bad idea, I mean even if it has a different fault it might be something!

I also looked back through my logs, back earlier in Jan and December I had these, ‘short circuit to ground’, ‘short circuit to b+’ and supply voltage.



I haven’t seen those for a while.

Could have indicated a bad pump or again wiring.

I’m just hoping it really isn’t the ECU, and whatever shorted didn’t damage something in it, that’s the last thing I want to change, and I’ll lose all my additional coding, map etc.

 

[T6_FunBus]

The vans been sat for two weeks (on trickle charge) as I’ve been busy with other stuff.

I took it for a run at lunch today, and have the same error (no surprises since nothing else has been done to it).

P16CB00

However this time accompanied by an annoying intermittent red battery warning light on the dash board. It would come on and go out itself after a time. Come to think of it, I have seen this crop up a couple of time before, and one of those was when I was fighting this heater support pump supply voltage error on the way to the garage to have them look at the pump (and ended up replacing it).

Central Electrics along with the red battery warning light kept throwing an intermittent 00446 - Function limitation due to insufficient voltage.

Battery is good (replaced under warranty a few months back as I suspected the old one was duff). Was also fully charged and 12.9 volts before going out today.

Alternator seemed to be working, it would sit not running for a bit and van would sit at 12.1v running from battery only, the alternator would kick in every now and then at 14.4v and revs increase due to load on engine at tickover? I do have a stop start error.

No other errors though, battery control module fine, no generator errors, etc.

Could this be related? And the heater support pump supply voltage error is a hangover / symptom of another problem?

I’ve googled 00446, and it points to fuses, battery or generator. I’m pretty sure all three of those are fine? If the generator was on its way out how can I tell? It seemed to be kicking in and giving good voltage?

The only thing that is a bit dodgy is the red wire to the battery module on the negative cable has started to split, I’ve been meaning to repair but haven’t got around to it, could this cause such an error? I’m not even sure what that module really does and what errors it gives if faulty?

I did have intermittent ‘reference voltage’ errors too at the same time the alternator wire was dodgy last Autumn.

To be honest, the van was fine up to the point that the alternator LIN wire shat itself and I had to redo it. But since I’ve not had battery module or generator errors, so would assume if they had an issue that there would be another error?

Bloody confused and pissed off. I can’t even be bothered to use the van anymore, hence it’s been sat for two weeks. Whenever I look at it I just see one big problem and it’s totally spoiling it for me.

Can anyone help to get this fixed once and for all please?

 

[T6_FunBus]

Ok so I went out tonight, and I removed the pin and resoldered a new wire on the Battery Module just to be sure, to be honest, the red wire although the sheathing was coming away was actually sound, but I had removed it so I resoldered a new wire to the pin anyway and refitted. It didn't help with the errors I am fighting.

I now pretty consistently have these two errors come back as soon as I clear them, and the red battery light seems to come on and go off randomly:

P16CB00 in 01 Engine (039 - heater support pump supply voltage)
> When this error is logged, voltage terminal 30 was 12.257v - seems fine to me?????
00446 in 09 Central electrics (Function limitation due to under-voltage 002 - Lower Limit Exceeded)
> No voltage information when error logged

I did have 1 occurrence of:
P16C100 (038 - heater support pump open circuit)

Before I started the van, battery voltage was 12.8, so full.
I cleared the errors, started the van and monitored live data and observed the following:

01 Engine
- 12.161V Voltage Terminal 15
- 12.055V Voltage Terminal 30
- 12.054V Battery Voltage
- 12.04V ESM_Battery_Voltage
- 3.2969V ESM_Sensor_Voltage
- 12.0000V Raw Battery Voltage

09 Central Electrics
- 10.88V Voltage Reference
- 12.16V Voltage Terminal 30

I then went back into 01 Engine and I loaded the system by putting on heater and lights, Generator load went from 0% scaled up to 48%
- 13.162v Voltage Terminal 15
- 13.150v Voltage Terminal 30
- 13.109v Battery Voltage
- 13.14v ESM_Battery_Voltage
- 3.2969V ESM_Sensor_Voltage
- 13.0000V Raw Battery Voltage

So I then went back into 09 Central Electrics:
- 13.18v Voltage Reference
- 14.98v Voltage Terminal 30

At this point Voltage Terminal 30 in 09 differed from 01, but that could be how it is supposed to be, or the generator load could of increased I do not know.

I then went into Battery Control Module which reports no errors, and selected various generator parameters, including temperature, signal, thermal etc etc, and all checked out OK. When I turned heater off or on, voltage / output scaled pretty much as expected in line with above.

So there we are. Not sure what all this means.

Given I now have two voltage related errors it could be the pump error is a symptom of the 00446 error, and whatever has caused that problem has steadily got worse so it now shows, or, the pump issue that is ongoing is the cause of the 00446 error!!!

I do not know enough to understand what reference voltage should be, and weather the fact it is almost always 1-2v lower than Terminal 30 is correct. The fact say with alternator off and no load it is 10.88v, would indicate to me, that if that is suppose to supply something with 12v, it is low, but again no clue if that is correct behaviour or not.

If someone can chime in and provide some help it would be appreciated, as now I have two errors, a battery light and a pump error so I am only going backwards...

The only thing that is different is I charged the battery while it was sat for two weeks, and I have only driven it once, I did charge from positive terminal and a chassis ground, but surely this shouldn't throw a battery warning light and the error above when cleared...

 

[T6_FunBus]

I had to pop out at lunch and monitored the battery, charging circuit and generator, and all performed as expected. Stop start even working. No battery light or error, so maybe that was a hangover from removing battery and charging the other day, I guess I’ll see if it returns.

But something else dawned on me, there are four 'heater support pump' circuits, I never really understood it since the 'heater support pump' is the one at the back of the engine, but looking into it further when error is reported there is:

Heater support pump 1 bank 1 second circuit activation: 95%
Heater support pump 1 bank 1 primary circuit activation 0%
Heater support pump 1 bank 1 second circuit activation 95%
Heater support pump 1 bank 1 charge air cool circuit activation 10%

So I checked live data and there are again four options - I checked this before but it didn't make much sense to me, but digging further it appears like this:

IDE07798
Heater support pump 1 bank 1 secondary circuit activation: this I assume is for the actual 'heater support pump' the one that supports coolant circulation in the matrix when parked up or stop-start. This almost always appears to (rightly or wrongly) be at 95%. This is the one the garage replaced as suspected it was faulty, and I have re-wired but have the same error. It works, and output tests (when not refused) work.

IDE07799
Heater support pump 1 bank 1 primary circuit activation: this I have no idea, it is always zero, parked, ignition on or off, engine running etc. It's weird, as you would assume the primary circuit would be the pump, but who knows what this is. My van to my knowledge only has three of these electronic water pumps, so, at a guess it could mean 0% is correct and this is not used? Who knows.

IDE07800
Heater support pump 1 bank 1 charge air cool circuit activation: safe to assume this is the charge air cooler electric pump - identical part number I believe to the other one I replaced. Located low down, front of engine near the bumper. Interestingly, I had to unplug these pumps when I was fixing the alternator LIN wire, as it runs in the same conduit. These wires come out of that conduit unprotected and connect to the connectors. Values on this vary, low load the % seems to be low, perhaps 10-20%, rising to as high as 95%, but for some reason, the % seems to be very specific, as in to decimal places, like 29.16%, dropping to 10%, up to 35.96% etc.

IDE11870
Heater support pump 1 bank 1 exhaust gas recirc cool circuit activation: safe to assume this is the third pump low down, right side behind front bumper, not sure if it is the same part number or not as I haven't looked. This seems to be fairly stable like the first heater support pump, we are talking 70% occasionally 100%.

So now onto my next thought. If I disconnect the plug to other pumps, it clearly says whether it is EGR, or Charge Air Cooler pump open circuit. But, for error P16CB00 'Heater support pump supply voltage', if the ECU treats all of those pump circuits as labelled above on live data as 'Heater Support Pump' circuits, then maybe, just maybe, all along it never really was the pump at the back of the engine. Perhaps it is a plug / wire or pump down low at the front that is at fault. These errors came about very shortly after pulling all that wiring down and out of the conduit to 'fix' and replace the alternator wire, so perhaps it is no coincidence and one of the wires or plugs was also on its way out to those bottom two pumps...

I am clutching at straws here of course. But it seems maybe the next check would be to look at the voltage at the connectors on the pumps at the bottom to make sure those pumps, wiring and connectors can be ruled out.

And now on to what really pissed me off, you would expect if you give your vehicle to a 'specialist' that they would know how to troubleshoot these things and replace the correct parts, and not have me running around trying to learn the damn stuff, guess and troubleshoot myself!

I could be barking up the wrong tree again here, but given the pump was replaced at the back of the engine with a genuine VW one, I did try a new plug, new power, new ground and new ECU wire and still got the error coming back, maybe, just maybe, I and the garage have been looking in the wrong place all along...

Thoughts and opinions from people who know better than me, and ideas on where to go from here appreciated. But I am thinking bin off looking at the rear pump and wiring for now, and maybe jack the front end up, pull the connectors on the other two pumps and check the voltage at the connectors there?

Hmmm.

 

[T6_FunBus]

Oh and just to add, I also monitored live data on the pumps, and voltages, such as generator voltage, battery voltage, terminal 30 voltage etc, and all behaved 'normally' in that there were no weird dips or spikes. Stop start even worked twice when I went across town to get lunch, and no battery light or low voltage error, so maybe that was a hangover from me charging the battery and / or removing it the other week when wiring in the new loom as I haven't used the van since. I guess I will see if that error or battery light returns, but it honestly all looked good on that side (coms to generator OK, thermal status OK, load / duty cycle, amps etc etc).

 

[mmi]

IDE07799
Heater support pump 1 bank 1 primary circuit activation: this I have no idea, it is always zero, parked, ignition on or off, engine running etc. It's weird, as you would assume the primary circuit would be the pump, but who knows what this is. My van to my knowledge only has three of these electronic water pumps, so, at a guess it could mean 0% is correct and this is not used? Who knows.

Agreed. On T6 the IDE07799 reports nothing. A partial installation list which pumps (and measuring values) are onboard is found in IDE10223-MASxxxx, where are shown three pumps - 2 active, 1 not installed. Perhaps IDE11870 doesn't belong to the group (IDE10223) hence totally different IDE-number?

 

[T6_FunBus]

Thanks for confirming @mmi

I haven’t had chance to check any other connectors, however, I did think about the heater support pump secondary circuit. This almost always shows 95%, in fact, I’ve never seen a situation on the old or new pump when it isn’t running at 95%.

I’ve read in some places the purpose of that pump is to run before the thermostat opens, but this was not specifically on T6. If that is the case the. This should change and lower output when the van is warm? Yet my 15 minute run accross town it stayed at 95% from start until I switched the engine off after the journey…

 

[T6Bob32]

Can we all chip in for another pump to rule out fail on fit, it's really grinding me gears

 

[T6_FunBus]

Can we all chip in for another pump to rule out fail on fit, it's really grinding me gears

Thanks Bob, to be fair, all I need is a known good pump to test, if anyone has one? But unlikely I guess. I could still get a used one off fleabay like you suggested. Not sure. My brains a bit pickled tbh working out what to try next.

 

[T6_FunBus]

Agreed. On T6 the IDE07799 reports nothing. A partial installation list which pumps (and measuring values) are onboard is found in IDE10223-MASxxxx, where are shown three pumps - 2 active, 1 not installed. Perhaps IDE11870 doesn't belong to the group (IDE10223) hence totally different IDE-number?

I still wonder if my theory stands about the ‘heater support pump voltage’ error, and that as they are all listed as heater support pump circuits in the ECU it could throw this error for more than one. I found a non-english forum thread and translated, the guy had the same error, but it was solved by changing two pumps, that doesn’t prove anything though than perhaps the garage changed the wrong one first.