Heater Support Pump and Voltage error woes

[T6_FunBus]

Put the van in for a heater support pump error with a specialist.

It has the following errors (starts off supply voltage eventually throws an EML).





Put it into a ‘specialist’, and asked them to check the wiring and supply voltage first.

They called and asked if I wanted them to change the pump, I told them to again, make sure they look at the plug and wiring first.

They called me later to say all done, so I picked it up and it still had the error in the ECU, I figured they forgot to clear it, so I cleared it. I use the vab this weekend and guess what, same error comes back

So must be a wire or connector… thats £300 I may aswell set fire to and now back to square one - me messing around with the wiring like I didn’t want to and didn’t have time to do, hence giving it to a garage so I’d have leas stress…….

I give up.

Anyhow, can anyone please help to provide any hints on where to look first. I assume I’m going to need to pull the airbox and inlet pipe to get to the connector, remove the D clip and get a volt meter and run output tests first. But if anyone has any diagrams or info or tips on common issues / where wiring goes etc would be appreciated.

A rather fed up and pissed of T6 owner…

 

[T6_FunBus]

Just got the D connector off in a few mins, sleeving is damaged, cannot see immediate damage to the wires yet but I guess need to test pins.

There is three, any idea which uis 12v, ned and assume lin?

 

[T6_FunBus]

Some pics

 

[T6_FunBus]

No matter what combo i use I cannot find a 12v on the pins?

Unable to run output test while its disconnected as well, any ideas?

 

[T6_FunBus]

Pin 2 in middle is live, 3 is negative.

Seems fairly steady, but blue wire (12v?) is damaged…

Waggling it around seems to not do much, could be shorting on the heat shield though.

 

[T6_FunBus]

I’ve made a decision to replace a crusty bit of 1” wire, but, its not going to be easy. Anyone have any ideas? Access for tools is very limited.

 

[T6_FunBus]

Back probed the blue wire, rhats at pin 1, voltage is fluctuating

 

[T6_FunBus]

No turning back now!

Blue / Purple wire supplies switch 12v from ECU and was fluctuating. Hoping the crusty section I’ve cut out is all that needs replacing. Time to struggle like crazy soldering down in there!!

 

[Craig.]

Which engine and year do you have?

 

[T6_FunBus]

hey Craig, its a 2016 150 tdi. Thanks.

 

[T6_FunBus]

I was wrong, purple / blue wire sends 12v back out the pump?

With that wire disconnected I get the following.

 

[mmi]

Black/yellow = +12V (fed from fuse SB29 (15A))
Brown = ground
Blue/purple = ECU

 

[T6_FunBus]

Thanks.

I’m honestly having a nightmare at the moment.

So other than having the pump replaced and spending out 100’s I didn’t need to, the garage also smashed my new front splitter, although did offer to replace, still un-needed hassle Now I’ve wasted a whole Saturday trying to troubleshoot an issue I didn’t want to which is why I gave it to them in the first place. I’m just so fed up. I’ve got enough on my plate atm and could so do without this. Its just really starting to get me down

I snipped off what I thought was the bad cm of the blue and purple wire. While it that wire which I now know is the ECU wire was cut, I plugged the pump in and it ran still. I let it run for a while with ignition on, and the only error was the ‘supply voltage - static’ error.

I tested the black / yellow wire and it was battery voltage.

The ECU wire seemed to also be battery voltage coming at the cut end coming out of the plug to the pump,

So I did a repair on the wire that looked a bit crusty, and soldered a new small bit in.



Awkward as hell but heat shrinked and wrapped it.

Reconnected, put air-box etc back, cleared errors - all good. Started up van and let it run - all good.

After a while though the bloody error was back

And now static…




Then I had a bloody EGR control circuit error come up /facepalm



I could clear but then they would come straight back…

I’m not sure if the EGR one was just a hangover from playing with the ecu connector to the heater support pump.

I cut the heat shrink of to inspect the ECU wire, and it was still soldered together and holding ok.



I tested either side of the ECU wire and voltage fluctuates, from anywhere between 0-10 volts or so when the pump is running. Measured both ends of the repair wire at the soldered joints and its reading same both sides.

I cleared errors several times, EGR control circuit fault went (although van was not running).

I again pulled the heater support pump connector and tested voltage with ignition on - it was solid battery voltage.

Plugged back in and back to intermittent supply voltage error again!

I just don’t know where to go tbh. Its cold, dark and I’ve given up.

Is there anyone who can help? Please.

 

[T6_FunBus]

I’m thinking maybe the best plan of attack is to buy a new connector, and just bypass the old loom and run a new 12v from the fuse box, a new ecu wire from wherever that connects, and a fresh ground?

I’m thinking it could take me, or whoever I give it to forever to unwrap and examine the wires on the loom and trace them all back?

That’s what I did with the alternator in the end, just run fresh wires from bcm etc rather than pissing about with the old loom?

I can’t at this stage think of what else it could be? If the pump is new (and it does look new), surely it has to be the wiring somewhere??

 

[T6_FunBus]

Can anyone identify this connector?



Looks same as this (but 90 degree).

If anyone can help with wiring also, where connections need to terminate I would really appreciate it. I’ve had a hell of a couple of weeks and just a bit drained, to dig through info.

Thank you guys.

 

[T6_FunBus]

Got the diagram page.



Looks like pin 43 only goes to ECU, so no danger rewiring that direct.

Is it worth re-wiring a new plug to a fresh ground (not sure where 1244 is in engine bay)?

And given supply voltage seems to be stable at battery voltage, is it worth wiring a new wire from t14f at pin 12?

I’ve been under the battery before, not sure what t14f connector is, but would need to splice into existing wire as it also appears to supply the oil pressure control valve.

I’m making an assumption the ECU monitors voltage on the coms on the blue and purple wire? Which IS the one that looked a bit crusty where I attempted a repair.

Hmmm….

 

[T6_FunBus]

OK I think I have a plan of attack, going to use a fuse tap on sb29, so its reversible, then connect this to a new connector as a test connector. Then get a fresh ground from a chassis bolt / mount, and connect to new test connector. Solder a new wire off of the blue and purple bit that attempted to repair today, then run it and check.

If the error still occurs, surely that has ruled out power supply and ground as they will be fresh, and as the garage fitted a new pump the pump? So then all that is left would be to renew ecu blue and purple wire on the old plug?

Still unsure how it monitors the voltage, but again had the static supply voltage error when I cut the blue and purple wire? It did not say coms error?

 

[Craig.]

T14f grey is in the vertical bank of 14pin plugs, in front of the relays.

I'd also confirm that they replaced the correct pump, there are 3 that are identical part numbers, 2 of which are positioned next to each other.

When I get the chance in about 45min, I'll dump some info on here for the ground point, wire routing and things to check.

Earth point 12, inside e-boxx (can't miss it, on the right hand side of the box)



Power as above, SB29 but this also powers other items (coolant valve for cylinder head, valve for oil pressure control, depending on vehicle spec) so get your alternative power from another source or use a spur.

You can use 0.5mm wiring for just the motor for a bypass loom, it's 1mm wiring down to the split as it feeds other items.

The signal wire is 0.5 throughout so that's fine too.

The next thing to check is where the wiring splits on the loom, connection D41, as this may have perished.

T14f will almost certainly not have an issue with power or ground as then you would have other codes for the same stuff that uses that power/earth. However, it would be prudent to check the plug on the ECU as they can have issues (water tracking up the loom etc)

The plug:



The pin code (for 0.5mm wire)

Got the diagram page.

View attachment 228377

Looks like pin 43 only goes to ECU, so no danger rewiring that direct.

Is it worth re-wiring a new plug to a fresh ground (not sure where 1244 is in engine bay)?

And given supply voltage seems to be stable at battery voltage, is it worth wiring a new wire from t14f at pin 12?

I’ve been under the battery before, not sure what t14f connector is, but would need to splice into existing wire as it also appears to supply the oil pressure control valve.

I’m making an assumption the ECU monitors voltage on the coms on the blue and purple wire? Which IS the one that looked a bit crusty where I attempted a repair.

Hmmm….

Don't make any changes at the T14f plug as that is before D41 and you will likely cause additional issues.

Just wire in an entirely new bypass solely for the pump and see what the result is

From my experience, the problem would be somewhere here, after D41 and more likely between the pump and ECU.



Just looking at the EGR pump, V400, fault which perked up as a matter of curiosity...



Interestingly, it shares the earth point in the e-boxx. Fused at SB27 so only 2 fuses over from the Aux heater pump. It goes to the ECU at the bigger plug so not likely a sign of the ECU plug having water ingress.... But everything is on the table at this point lol!

Probably nothing but worth noting.

 

[T6_FunBus]

Thanks so much, loads of helpful info here! So I won’t touch t14f, my plan is to use a fuse tap on sb29 for a fresh power supply and then locate a fresh ground, and connect the ecu wire to the part that I soldered (and have now cut the sleeving ofd) first to see if the issue goes away. So old ECU wire, new live and ground. I guess if that does not work then its back to refreshing the ecu wire somehow.

I also unplugged the two pumps at the front to check what they are reported as. One front nearside above subframe near rad - charge air cooler pump. One in the middle front rad behind subframe = egr cooler. One at the back is defo heater support pump and this one is fresh and shiny, while the others are dirty / dusty, so they appear to have changed the right one. And they told me they only use dealer parts as aftermarkets can give faults, hence £200 just for the part I guess.

I’m just going out to brave the weather and have another look. Will report back.

 

[Lubrown]

Thanks so much, loads of helpful info here! So I won’t touch t14f, my plan is to use a fuse tap on sb29 for a fresh power supply and then locate a fresh ground, and connect the ecu wire to the part that I soldered (and have now cut the sleeving ofd) first to see if the issue goes away. So old ECU wire, new live and ground. I guess if that does not work then its back to refreshing the ecu wire somehow.

I also unplugged the two pumps at the front to check what they are reported as. One front nearside above subframe near rad - charge air cooler pump. One in the middle front rad behind subframe = egr cooler. One at the back is defo heater support pump and this one is fresh and shiny, while the others are dirty / dusty, so they appear to have changed the right one. And they told me they only use dealer parts as aftermarkets can give faults, hence £200 just for the part I guess.

I’m just going out to brave the weather and have another look. Will report back.

Feel your pain with not trusting garages.
I’ve had several incidents including one removing the engine… with one bolt still in place (they had to keep the car for over a week to mend and re-tap the engine mount, a different garage ripping the ABS sensor wires while working on the front… had the managers car while they waited for spares, and a body shop who did a lovely job repairing a deep scratch all down one side from a keying/trolley incident only to add a deep dent into the sill. They argued it wasn’t them but when I walked into their workshop and pointed at the pad at the end of the arm on the lift, oddly the same size, shape and height off the ground as the fresh dent in my sill, they stopped arguing and decided they could repair it “out of good will”.

I use a couple of local specialists now. One is sketchy on keeping appointments but is otherwise good. The other is good enough but always looking to make an extra £2 on a service by topping up the screenwash… even when I brimmed it before dropping off the van. Supposedly he’ll knock that off the bill next time.

Is it really that hard to just do an honest job?