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P261C - Aux Coolant Pump

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#21 ·
New2Tregs said:
VW, in the infinite wisdom, decided that on the T3 with the VR6 engine they would put it in a difficult spot.
I would have loved if they had put it in the fender well as I would have swapped it out already.
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Oh I didn’t see a model year in your original post or signature. So where is your aux pump?
 
#22 ·
Mexglx said:
Oh I didn’t see a model year in your original post or signature. So where is your aux pump?
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Stuffed between the back of the engine and the firewall, about 12 inches or so down.
The most lovely of places to get to. :LOL:
 
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#23 ·
gazaflash said:
I have the same issue. I removed the pump and checked for continuanty on the windings and got nothing so assumed I found the problem…!
What a pain to change the pump. I bought a pump from the dealer as the system is very sensitive to having the correct load and correct resistance. Didn’t want to get some dodgy eBay look a-like!
I only fitted 1 torx bolt back on the bracket as it is a pain getting in all back in.
After vacuum filling the cooling circuit to ensure all air pockets were filled, I cleared the codes and about a day later, the CEL is back!
I guess I have to check to see if the new pump didn’t burn itself out because of some other issue.
I’m just gonna untick the box for aux water pump or “rest function” if this keeps up!
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@gazaflash any luck or progress with this?
 
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#24 ·
Yes, I was there multiple times. Resorted to assisting my thin and light lanky mechanic. He needs to kneel lightly on the engine top cover and also other leg on high stool. Then need monkey like arms to convulate in.

Let me update on my last few post. This pump is wired directly from ECU to Pump, 3 wires being +, - and signal. There is no fuse or relay in between. As my previous connect got burned out, I changed a new one, spliced extra length of good copper, and added a fuse junction inbetween. I was concerned high draw might burn my connector again, but was pleasantly surprised the 3 or 5A fuse I added did not. So things are well protected, for another few years till pump blows again.....cheers
 
#25 ·
emailpeter said:
Yes, I was there multiple times. Resorted to assisting my thin and light lanky mechanic. He needs to kneel lightly on the engine top cover and also other leg on high stool. Then need monkey like arms to convulate in.

Let me update on my last few post. This pump is wired directly from ECU to Pump, 3 wires being +, - and signal. There is no fuse or relay in between. As my previous connect got burned out, I changed a new one, spliced extra length of good copper, and added a fuse junction inbetween. I was concerned high draw might burn my connector again, but was pleasantly surprised the 3 or 5A fuse I added did not. So things are well protected, for another few years till pump blows again.....cheers
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Thanks. I did read your procedure in post #44 of the thread in the link below.
I was able to solder on a new plug as the old one was pretty corroded. Used shrink tubing on each wire for separation and then shrink tubing over all the harness to protect the harness I had cut open to expose the original wires. All looks neat.
I plugged the new pump into the harness/plug but have not yet swapped out the coolant lines from the old pump to the new one. I still get P261A - Open Circuit. I would have thought the CEL would stay off with the new pump/plug installed.
Previously I had both P261A - Open Circuit and P261C- Short to ground.
Do you know what the S(signal) wire is for?

Link >>>> https://www.clubtouareg.com/threads...-pump-2-mil-on.256242/?post_id=2092664&nested_view=1&sortby=oldest#post-2092664
 
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#26 ·
I think you will be all right. I'm not an electrical expert to that level, but was told, the S wire controls the oscillating wave signals to and fro ECU to Pump motor. Such that varying voltage can adjust pump speed.

I think your open circuit error is related to the air spinning pump not showing its flow of coolant to some temp to pressure sensor inside system. Plug it in and prob solves it. But do not use any non-Pierburg pumps, let alone any Aliexpress ones. As I encountered the ECU is darn sensitive to those S signals above, slight off will throw you that CEL. You really don't want to repeat the task (hahahahaha).
 
#27 ·
emailpeter said:
I think you will be all right. I'm not an electrical expert to that level, but was told, the S wire controls the oscillating wave signals to and fro ECU to Pump motor. Such that varying voltage can adjust pump speed.

I think your open circuit error is related to the air spinning pump not showing its flow of coolant to some temp to pressure sensor inside system. Plug it in and prob solves it. But do not use any non-Pierburg pumps, let alone any Aliexpress ones. As I encountered the ECU is darn sensitive to those S signals above, slight off will throw you that CEL. You really don't want to repeat the task (hahahahaha).
Click to expand...
I have an OEM VW/Audi pump. I don't see the Pierburg name on it at all.

Image
 
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#29 ·
emailpeter said:
It is. Go ahead plug it all in. You're good for another 5 yrs+.
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Electrically it's all connected. I go the bracket holding the old one released. I just have to remove the old one from the coolant lines and swap this one in. In the next week or so hopefully.
 
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#30 · (Edited)
UPDATE-
Had some time this weekend so I decided to finally swap in the new pump on the coolant hoses. What a PITA to get to and reinstall the hose clamps. Got everything back together, plugged the electrical connector in and BAM got he check engine light again. Code P261A Open circuit for secondary coolant pump. For S&G's I checked fuse #12 in the engine bay as it's labeled as a 10A fuse for the secondary coolant pump. The fuse is good.
I'm at a loss and that damn engine light is still on.
Anyone have any ideas?

EDIT- I decided to look at the original pump. Turns out the number on it is 059-121-012B. I'm wondering if the reason I'm still getting an open circuit code is that I installed a 059-121-021B. Knowing how finicky these VW systems are it wouldn't surprise me.
 
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#31 ·
New2Tregs said:
UPDATE-
Had some time this weekend so I decided to finally swap in the new pump on the coolant hoses. What a PITA to get to and reinstall the hose clamps. Got everything back together, plugged the electrical connector in and BAM got he check engine light again. Code P261A Open circuit for secondary coolant pump. For S&G's I checked fuse #12 in the engine bay as it's labeled as a 10A fuse for the secondary coolant pump. The fuse is good.
I'm at a loss and that damn engine light is still on.
Anyone have any ideas?

EDIT- I decided to look at the original pump. Turns out the number on it is 059-121-012B. I'm wondering if the reason I'm still getting an open circuit code is that I installed a 059-121-021B. Knowing how finicky these VW systems are it wouldn't surprise me.
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Oh no NewTreg. I just realised I didn't study your earlier picture properly. That 021B is for 3.0T V6 Tfsi. Our 3.6L VR6 uses 012B. My apologies not checking your details.

Yes. It's a hugely sensitive piece of @#£&#@?! plastic lump of trouble some pump....lol.

I am 99% certain it's the reason for CEL. BTW, there is no fuse for our pump. It has a cutoff inside the ECU, nothing more. Guess you just joined my club, the repeated fixing 2x.....Hope you solve that soon.
 
#33 ·
emailpeter said:
Oh no NewTreg. I just realised I didn't study your earlier picture properly. That 021B is for 3.0T V6 Tfsi. Our 3.6L VR6 uses 012B. My apologies not checking your details.

Yes. It's a hugely sensitive piece of @#£&#@?! plastic lump of trouble some pump....lol.

I am 99% certain it's the reason for CEL. BTW, there is no fuse for our pump. It has a cutoff inside the ECU, nothing more. Guess you just joined my club, the repeated fixing 2x.....Hope you solve that soon.
Click to expand...
Not your fault and I appreciate the clarification.
Oddly enough when going through my parts hoard, due to my OCD, I found I had ordered a 059-121-012B at some point so I have one on hand.
I'm going to bite the bullet and swap them tomorrow. Thankfully I left the hose clamps in a position so that they can be moved a lot easier. I will report back when done.
 
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#35 ·
The 002 probably has a different resistance hence why my Treg doesn't like it and throws the CEL.
I'm definitely going to remember this for others that want any info on replacing the pump.
 
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#36 ·
Took the time today to replace the aux coolant pump again. Put in part # 059-121-012B. Same issue. After third startup the CEL came on. Checked and it's the same code P261A open circuit.
What a disappointment.
 
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#37 ·
@New2Tregs, so sorry to hear. We have shared numerous frustrations, as many know, we need feed new coolant, pressure test and circulate, and R&R manifolds, airbox etc. I did it 4x in total to get it fixed. Which explains why I have so many photos of owning so many versions of the @#___#+-*" pump.

Treg, as you know, there are 3 wires that go directly to ECU. It's really all that is. Do recheck your wires & connector, as I burnt out (connector and pump socket & housing) 1 week after my 3rd fix, I think it was shorting at pins, or water ingress. The ECU autocuts it's pump relay on any shorting, no fuse or relays externally. Fitted a totally new connector built from scratch, and new wiring added. There is hardly anymore variables to this wiring.

Good luck buddy, I wish you well, and fixed soon.
 
#38 ·
Here are more photos of burnt connector. And the inside circuit of spoilt pump. I think the S-signal is an ossilator reader that tells the rpm and voltage of pump. And ECU reads and controls that. Given the complication of resistors, capacitors and IC's, one can see how a CEL is easily up when deviations occur.

Treg. Patience and persevere. We all feel the pain on overstudying and overworking that silly convoluted pump.

Image

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#39 ·
My connector was nowhere that bad, that's definitely bad. Mine just looked corroded. I replaced it with the one in the pic below. Soldered the wires together and put shrink tubing over each wire to isolate them and then put shrink tubing over all of them afterwards.

So I spent more time on this tonight. I decided to check fuses in the engine bay as according to the PDF file I found on here about fuses it said that fuse #8 in the engine bay was related to the coolant pump. That 10A fuse was bad. I attached the fuse PDF. I replaced that fuse and will find out in the next day or so if it made any difference.

I also want to say thanks for providing all the info and pictures you have. Extremely helpful and I appreciate it.

I will post back as to whether or not that fuse replacement has made any difference.

Image
 

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