Instrument Cluster issues after rebuild

[Steve Addy]

Well I posted up specifics about the parts in the "what did you do..." thread today, the parts are NLA from VW and by extension they'll be NLA from ECS too...since ECS doesn't stock anything. Further, ECS is notorious for not marking anything NLA until you ask about it, and then they do something about their listing...maybe, but maybe not too...they're horrible about it.

At any rate there's information about this stuff here in that thread and also as I said the "what did you do to..." thread.

Parts application is limited, where it says Jetta, Golf and Passat it should just say Jetta TDI, Golf TDI and Passat TDI instead. Whether the Eurovan stuff is actually correct I cannot say.

There are people parting TDI's on FB though, they might have it, or someone else might have a roached out rotted TDI they're parting and would cut it off.

I've never liked to cut harnesses apart that way on a Mk3 or B4 TDI but anything else is fair game. I like to keep the engine harnesses intact if I can because those are somewhat precious to have, however, if a harness has been ravaged by rodents then it's also fair game for dismantling to keep another car on the road. The same for a T68 ECU connector, those for TDI are good to have with some lengths of wire coming out just in case you need to rebuild something. I'll look next time I'm down to the shop but I don't recall having one of these separate from an engine or a complete harness.

Steve

 

[Steve Addy]

Yeah, I saw the ECS listing but had the same thought that you did. I've been looking overseas too with no luck. I looked for wiring harnesses on car-part too but most are 2.0's or they don't specify the engine. This is going to take some digging.

An older post in the conversion forums mentioned an aftermarket 24 pin connector but I haven't been able to find that connector yet either.

https://forums.tdiclub.com/index.ph...engine-electrical-connector-round-ahu.390630/

I've seen that online too in reference to that old thread but have not found it for sale. It certainly did exist at one time but who knows now.

I will say though that you don't need a 24 pin connector, you only need a 17 pin connector, a full 7 of the ones in the T24 are unused, and if you count the unused TDI oil temperature sensor connection that has a wire but isn't used then you actually only need a 16 pin connector.

Steve

 

[turbodieseldyke]

Not just the # of pins, you also need to account for wire gage. The orb pictured seems to have 5 large, 2 medium, and 10 small connectors.

 

[Steve Addy]

Not just the # of pins, you also need to account for wire gage. The orb pictured seems to have 5 large, 2 medium, and 10 small connectors.

Absolutely true, I just assumed that the need for sized cavities was a given, but you're right about the gauge being an issue.

It still might be easier to find a candidate with 16/17 pins versus 24 though.

Steve

 

[kmjunge]

I was thinking the same thing. I messaged Dave from TDC Shop to see what his solution was and he said on his harnesses he essentially deletes the T24 running wires direct for things such as VSS, glow plugs, oil pressure, and ECT.

 

[kmjunge]

I was able to further confirm that the T24 is my main issue. I popped it out of it's bracket and zip tied the **** out of it. This is how it went:

1 zip tie - no change
2 zip ties - tach works, fuel gauge works, no speedo, buzzing oil pressure warning
3 zip ties - tach works, fuel gauge works, speedo works, temp gauge works, no oil pressure warning

I essentially had to apply pressure from multiple different directions in order to get everything to talk. Once I can get my hands on a good connector I should be good to go.

 

[Steve Addy]

I was able to further confirm that the T24 is my main issue. I popped it out of it's bracket and zip tied the **** out of it. This is how it went:

1 zip tie - no change
2 zip ties - tach works, fuel gauge works, no speedo, buzzing oil pressure warning
3 zip ties - tach works, fuel gauge works, speedo works, temp gauge works, no oil pressure warning

I essentially had to apply pressure from multiple different directions in order to get everything to talk. Once I can get my hands on a good connector I should be good to go.

Actually, I'm going to guess that all you really need is the harness side with the tightening wheel and weather seal? I don't see any reason why the other piece would need to be replaced unless they completely destroyed that during the removal?

I recognize that these things can be frustrating, but a channel lock pliers gently twisting back and forth will eventually get the latch to unlock. It's because they've never been undone that's the reason they're reluctant to move at all.

Steve

 

[kmjunge]

Yeah exactly, all I need is that harness side. But I need 2 of them. One for the Jetta and one for my van conversion. The one on the van is less broken but definitely not getting a good connection. I was the one who broke the one on my van last year when I was pulling the engine from the donor car. That was a sick feeling...

 

[Abacus]

So all you need is that part? That’s a lot easier to get than both sides.
There is only 1 there, sorry.

 

[kmjunge]

Yeah I'm just looking for the harness side with the twisting piece. 1 is better than none.

 

[burn_your_money]

Could you use the connector that’s by the hood latch instead? I haven’t looked at one in a long time but I’m pretty sure it has some heavy wires in it. Perhaps it’s still available?

 

[burn_your_money]

So it just so happens that the car I am working on has a broken T24 connector as well.
I'm looking at the following links and wondering if they can be made to work. This is just some preliminary research, I don't know if any of it works

Connector https://www.te.com/usa-en/product-796207-1.html
Other side of connector https://www.te.com/usa-en/product-796203-1.html

Link to catalogue with pin sizes, drawings etc https://www.mouser.com/pdfdocs/CPC-Catalog.pdf

 

[Steve Addy]

Could you use the connector that’s by the hood latch instead? I haven’t looked at one in a long time but I’m pretty sure it has some heavy wires in it. Perhaps it’s still available?

You're talking about the connector at the radiator on Mk3 cars? The one for front lighting? I think that connector is 15 pin but I don't know if it has any cavities that will allow for big wires like the one for TDI engine.

So it just so happens that the car I am working on has a broken T24 connector as well.
I'm looking at the following links and wondering if they can be made to work. This is just some preliminary research, I don't know if any of it works

Connector https://www.te.com/usa-en/product-796207-1.html
Other side of connector https://www.te.com/usa-en/product-796203-1.html

Link to catalogue with pin sizes, drawings etc https://www.mouser.com/pdfdocs/CPC-Catalog.pdf

I would think rewiring both sides of the T24 would be a lot more time consuming to do than finding the side with the locking wheel...then again maybe there are just that few out there anymore, who knows.

I will check my stash to see if I have any that aren't attached to full intact TDI harnesses.

Steve

 

[kmjunge]

I checked another yard an hour or so from my area that has some Mk3 stuff but they didn't have any TDI's. I checked the plug from a VR6 Passat and it was not a match. I placed an order through ECS just to see what would happen and that went exactly like we expected. 2 days later I got an email saying it was NLA and a refund.

My zip tie hack is still holding up but I'm leaning more towards taking Turbo Dave's advice (TDC Shop) and just deleting the connector and running everything directly to it's home. That would mean lots of cutting and connecting and soldering but probably better than zip ties for the long run.

 

[Steve Addy]

I checked another yard an hour or so from my area that has some Mk3 stuff but they didn't have any TDI's. I checked the plug from a VR6 Passat and it was not a match. I placed an order through ECS just to see what would happen and that went exactly like we expected. 2 days later I got an email saying it was NLA and a refund.

My zip tie hack is still holding up but I'm leaning more towards taking Turbo Dave's advice (TDC Shop) and just deleting the connector and running everything directly to it's home. That would mean lots of cutting and connecting and soldering but probably better than zip ties for the long run.

I'm assuming Mark got you one from that Arizona junker, if you can just hold out a short while I bet you'll get what you need to fix it.

Steve

 

[kmjunge]

That's the plan, just considering alternatives. I really don't want to chop up any more wires that I need to.

 

[burn_your_money]

You're talking about the connector at the radiator on Mk3 cars? The one for front lighting? I think that connector is 15 pin but I don't know if it has any cavities that will allow for big wires like the one for TDI engine.

I think so. I looked quickly at it and thought there were some decent sized wires. 15 isn't enough though anyways.

I would think rewiring both sides of the T24 would be a lot more time consuming to do than finding the side with the locking wheel...then again maybe there are just that few out there anymore, who knows.

I can't imagine the ones out there being in much better shape but you never know. I guess for how often that connector needs to be taken apart it isn't really that big of deal to just delete it.

 

[k8t415]

I have a '97 Passat TDi and was following along because I had the same issue with speedometer/instrument panel, did some troubleshooting and it seemed to be the T24 cluster. I gently unscrewed it and pulled the two pieces apart to check for any corrosion or visible issues. Didn't find anything, but on plugging it back together now the car won't start. Any ideas what I did wrong or what I should do from here? There was no issue with the car not starting before this. I have only basic car knowledge so it may be something obvious that I don't know.

 

[ToddA1]

I’d take it apart again, and reconnect it, ensuring it’s fully seated.

-Todd

 

[burn_your_money]

Add a bit of dielectric grease or silicone spray to the main seal. That will help it seat fully.

 

[k8t415]

In trying to figure out this speedometer issue (I have no gauges, no speedometer/gas gauge/odometer), it seems like I have an issue with the #12 pin/black and white wire that runs to the fuel shutoff solenoid. It is just not making contact but all the other wires in the T24 are fine. From the ECU pin 53 to the T24 is fine and from the male side of the T24 for the solenoid is fine. If I’m understanding this wiring stuff correctly, my options are either to take the black and white wire out of the female side of the T24 where the problem is and try repinning it, or just cut the black and white wire on both sides of the t24 and make a direct connection outside of it? Sorry if I’m getting any of these terms wrong, this is my first time messing with anything beyond brakes and oil change. I have the lite VCDS running on my laptop and the fault codes are 01237, 00522, and 01050. If I can figure out how to post pics I will but my brain may be maxed out just with VW wiring right now. I’m also having an issue with the red and black wire that runs from the starter to the ignition switch, it seems to have an issue in the control module but that’s a whole different post lol. Have just replaced the bad battery and starter.

T24 cluster

• k8t415
• Dec 21, 2021

lining up the red/orange line to put the two T24 pieces together

• k8t415
• Dec 21, 2021

Wires going into the female side of the T24

• k8t415
• Dec 21, 2021

You can see the black and white wire that goes up to the ECU goes into #12 slot

Fuel shutoff solenoid with the black and white wire

• k8t415
• Dec 21, 2021

Goes up to ECU pin 53

What is this?

• k8t415
• Dec 21, 2021

Between fuel shutoff solenoid and the male side of the T24. No idea if this goes into something...

Grounds near battery

• k8t415
• Dec 21, 2021

T24 in fully locked position

• k8t415
• Dec 21, 2021

You can see the piece that gets turned with the red line all the way to the right

T24 stationary male piece

• k8t415
• Dec 21, 2021

This part seems good

T24 cluster, inside female part

• k8t415
• Dec 21, 2021

Having an issue at #12

 

[ToddA1]

With all that’s not working, I’d be checking the ground at the stud, where the t24 connector is. I’m sure it’s been mentioned in this thread. The cluster pulls ground from there.

Another member had the same issue and the ground wire was corroded, under the insulation. Video is on YouTube, under Pine Hollow Auto. The wire can be probed to confirm. A quick test would be a jumper from the battery, to the eyelet.

That control module is just a starter kill. I bypass it with a jumper wire, at the harness plug. Look for the thickest 2 red wires, and insert your jumper, between them.

-Todd

 

[k8t415]

With all that’s not working, I’d be checking the ground at the stud, where the t24 connector is. I’m sure it’s been mentioned in this thread. The cluster pulls ground from there.

Another member had the same issue and the ground wire was corroded, under the insulation. Video is on YouTube, under Pine Hollow Auto. The wire can be probed to confirm. A quick test would be a jumper from the battery, to the eyelet.

That control module is just a starter kill. I bypass it with a jumper wire, at the harness plug. Look for the thickest 2 red wires, and insert your jumper, between them.

-Todd

I will check right now, thank you!

 

[burn_your_money]

Did you try putting a bit of lube on the connector seal and seeing if it goes all the way together? Your symtoms are almost identical to what I was dealing with. Once the connector was fully seated most of the issues went away. Both ground wires were also broken internally that are on the stud below the T24. I load tested the ground wires from the stationary connector to confirm where the issue was.

 

[Steve Addy]

I recommend a little dielectric grease on the connections, makes it less likely for the connectors to resist going together.

IIRC a while back someone mentioned that one of the wire connectors had backed out of the housing when putting it together.

Ditto what everyone said about the grounding stud.

Steve

 

[k8t415]

It started to rain so I’ll have to wait til the morning to run any more checks. I did take apart the ground under the T24 and inspect it visually, didn’t see anything obviously awful but I’ll run tests with the battery tomorrow. And def grabbing some dielectric grease at the auto parts store tomorrow, too.

Ground under T24

• k8t415
• Dec 21, 2021

The wires that are grounded under T24

• k8t415
• Dec 21, 2021

Where the wires are grounded under T24

• k8t415
• Dec 21, 2021

Sad Passat in the rain

• k8t415
• Dec 21, 2021

 

[Abacus]

That lone connector is for the oil temp sensor, which you don’t have. The cars were pre-wired for stuff like that, which came on the GLX.

 

[k8t415]

That lone connector is for the oil temp sensor, which you don’t have. The cars were pre-wired for stuff like that, which came on the GLX.

Aha!! Mystery solved, thank you!!!

 

[kmjunge]

FWIW, my car had that white/black wire cut and bypassed around the T24 by the previous owner. All the issues you're having do seem to culminate at the T24. I had all those same codes and the timing was pegged at 255. Have you had it running to check the timing? When I finally diagnosed my bad T24 connection I was working on the timing. I pressed the T24 together by hand even though it looked like it was already connected and I found that when I pressed it together the engine timing got better (it was on the graph). While I had it pressed together I cleared the codes and did another check for fault codes and it came back clear. When I let go of the connection the codes popped back up.

 

[k8t415]

Where do I put the dielectric grease on the T24? On the actual little metal plugs/pins, or just inside the tightening bracket? Sanding and checking grounds now too.