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.