MK5 BRM Engine Harness Replacement

Hello curious if anyone has any advice on replacing a BRM engine harness? I have a 2006 Jetta TDI Manual that has been acting up. A few months ago the cam sensor wire failed resulting in long starts so I just ran a new wire and spliced it in all the way to the 60 pin connector at the ECM.

Well that bought me a few months but a couple days ago the engine just died while driving. I coasted to the side of the road waited a hour and thankfully it started. Hook up the VCDS pulled this code.
1 Fault Found:
005731 - Control Circuit for PD Injectors
P1663 - 000 - Short to Plus - Intermittent

Makes sense the injectors wires are located in the same harness. Anyways attempted to pull the engine harness out because multiple wires are chewed up where it chaffed against the plastic shielding near the starter under the air filter box. VW really dropped the ball when they engineered this mess.

To my question what would be the easiest way to disconnect the crankshaft speed sensor? its in a really tight spot. Also it gets really tight around the tandem pump area. I really would like to avoid removing coolant hoses if possible thanks.

I've done a lot of these.

First, make sure you can actually GET a new harness. Some are NLA. There are a few different ones for the BRM, but basically it distills down to early or late, manual or automatic.

Early has the glow plug circuits in their own connector back behind the left headlamp, late has those circuits integrated into another connector down lower towards the radiator.

Manual has the starter signal wire included, automatics do not (that wire is part of the transmission harness on those).

Get a new water flange (comes with a seal) on the head. It is MUCH easier to get the harness swapped with this removed, and you won't want to reuse it as they rarely ever seal properly again. You'll also need the o-ring for the sensor in the flange.

Good time to replace the tandem pump gasket too, and if there are any signs of fuel leak, the pump itself.

I use a cotter pin removal tool and a long screwdriver to remove the CKP sensor connector. Use the screwdriver to gently push the connector ON, then use the pick to gently pull back the release, then pull the connector off. Study the new one to see how it works (it is the same basic type most of the connectors on the car are). Removal of the oil pressure sensor (the connector has to come off anyway, as that is part of the harness) will make seeing down in there easier. I've never had to remove the oil filter stand to gain access.

Pay attention to the routing, it only fits properly one way. Take pictures if you need to. Not a hard job, just tedious. Take your time and be patient with getting it back in properly.

Thanks oilhammer that's the info I was looking for. Well I have the time so I am going to remove the harness and try and repair it. I'll go through the entire wire harness splicing some new wires with heat shrink butt connectors where its needed then wrap it in friction tape. I just refuse to pay the $750 cdn the stealership wants for a new wiring harness.

Learning these MK5 TDI Jettas are pretty pricy to maintain properly, If I wasn't mechanically inclined I'd probably want to burn it by now.

Any advice on the main connector, the one that goes under the windshield?

Follow-UP

Hey Chad... how'd this go for you? Currently looking to replace harness for same model (06 Jetta TDI - Manual Trans). Did you replace the items recommended by oilhammer? Trying to locate them online now. Possibly have any links to the items... especially the "o-ring for the sensor in the flange?" Thanks in advance!

I did both of my BRM Jetta's earlier this year and I replaced the coolant flanges (around $10) but I had recently replaced the tandem pump seals so I didn't bother with them. The first car took me 3 hours hours and the second car took me maybe two hours. The hardest part of the entire ordeal was getting the wiper arms off of the wiper motor linkage. I had to buy a windshield arm puller from Amazon but even then they barely budged. The other thing that I did is I pulled the oil pressure sensor out to get down below it to reach the CKP sensor.

Bigpoo5125 said:

Follow-UP

Hey Chad... how'd this go for you? Currently looking to replace harness for same model (06 Jetta TDI - Manual Trans). Did you replace the items recommended by oilhammer? Trying to locate them online now. Possibly have any links to the items... especially the "o-ring for the sensor in the flange?" Thanks in advance!

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Sorry for the much delayed response I usually only come around when my Jetta gives me problems. If I remember correctly I ran a couple really bad wires along the wiring harness to the ecm as a temporary fix. I bought a BRM parts engine and robbed the wiring harness but never got a chance to install it a few months after I started this thread I hit some black ice and wrote my Jetta off. I replaced it with another identical 2006 Jetta TDI.

Hey all -
Our good ole '06 Jetta TDI is holed up in upstate NY. .. It's at Maguire VW Ithica having the glow-plug circuit section of the 1.9l BRM's engine wiring harness replaced. .. That and a glow plug. ($945.)

We'll see. .. Sure do wish Ithica was closer to St. Louis . . . .

oilhammer said:

Manual has the starter signal wire included, automatics do not (that wire is part of the transmission harness on those).

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I know this is a old thread but it seems to be one of the only ones I can find that directly address this. The 2006 BRM DSG 03G-972-619-KN harness seems long gone on availability, those that still list it online come back with "NLA" when asked. Have you had any experience modifying a 03G-972-619-KM M/T harness? If the only difference is the starter signal could it work? If I had the detailed diagrams for both the DSG and MT I would blow them up and trace them wire by wire, but I cannot find those diagram either. My harness is beyond salvage, and I don't trust a used one for obvious reasons. Thanks in advance.

You could probably figure something out if you had them both out loose in front of you.

oilhammer said:

You could probably figure something out if you had them both out loose in front of you.

Click to expand...

I don't think my current harness is electrically traceable anymore; too many breaks. I could remove it and take all the covers off and trace the wires themselves. I would need to commit for a $300-$400 MT harness. I would love to start with diagrams. I was hoping you already needed one in the last couple of years and went through this, but thanks for the quick response.

I have a DH suffix one here NIB. Which ETKA shows is for the automatic. There are eight total part numbers for BRM harnesses. In addition to the manual or automatic, there is also early and late, because some have two connectors near the headlight, and some have all those wires integral in one connector. I have had to do that modification before. That's really the only differences I know of, but that would only account for four different ones, so there must be other differences.

These harnesses have been NLA, then back available, a few times for me now. Which is why I pester people to grab one when they can.

edit: just got off the phone with our dealer parts guy. KN, AL, and AN suffix harnesses (all automatic) are NLA. KM, AK, DF, AM, are all available, all for manuals. The DH harness is the only one still available for the automatic, which is I think why I got that one, because I was going to try and make it work on the next one that came in.

I am betting you can get the DH harness to work. The difference will be that you make have to change a couple wires at those connectors near the headlamp.

If you get your entire harness out of the car, and take a few pics, I can compare it to what I have here and we'll see if it can be made to work.

The manual one would probably work, too, you'd just have an extra wire for the starter that you won't need. But I wouldn't know WHICH manual harness to get that would be the closest to yours.

All great info. I would guess the KM would be closest to my KN because it falls into the same VIN Range, late 2006. It should also have the same connector as mine in front of the battery There is also something about being an early and late harness regarding the glow plug harness being integrated or not, mine was integrated, before put in a new one glow plug harness in and connected it to the harness right off the connector at the fuse block.

I was proactively trying to have a harness ready buy won't be able to pull my just yet, I am in the middle of a Smyth conversion (that got delayed mid-conversion due to shoulder surgery).

I may just pick up a KM and take my chances, lay them side by side and physically chase the old one while I electrically trace the new one. Following wiring doesn't bother me too much, except dealing with old brittle failing wires and connectors where you fix one thing only have another pop up. The car will run and drive, but it throws some fault codes and then goes into limp mode on sustained driving like the freeway.

If you can, post some pictures as this may help more folks going forward. I still service a lot of BRMs, just had one in here with over 417k miles on it, so a harness replacement may be something more and more will need done (that one just had its harness replaced recently).

Will definitely document it and add and update. I purchased the Mitchell wiring diagrams last night and started reviewing them. All the engine control wiring in that connectors seems consistent and the same. I did find on error or inconsistency in their diagrams, wire 47 if I recall went to the egr on the engine diagram, but to the throttle position sensor on the cruise control diagram. My notes are at home. There are 60 pins on that connector, all but 17 are accounted for. Those are either blank pins or they go somewhere that doesn't show in the diagrams, that is where the wire by wiring tracing will send me. I did not see the MT starter wire called out either from that harness, so it may be in that mix too. It may be a couple months, but I will definitely follow up.

If you are using Mitchell's "non-OE" diagrams, they are full of mistakes and different nomenclature. As in, there is no such thing as a "throttle position sensor" on a BRM car. And the "cruise control" doesn't have anything at all to do with anything on the engine management whatsoever. It is all integral to the ECU, and the switches (be they all on the stalk, or the steering wheel, or whichever version) all go to the Steering Column Module, along with the "ignition switch" (which really is more of a key position sensor) and other signals, that are in turn broadcast down the CAN Bus to whatever module wants to see it.

Also, the engine harness is JUST the stuff that goes to the engine itself (minus the alternator/compressor). It does not include the MAF, MAP, Lambda, any of the pedal inputs or anything at all from inside the car, nor any CAN lines.

Got it. I also found your other thread on this that shows everything it touches. You have 4 harnesses on that thread, and early and late. Now I am confused as I saw early and late production dates, but there you have a VIN cutoff. Based on your Vin cutoff there, and my vin as 699541 it now appears I should have the DH harness. My build date is 10/05, MY 2006. When I do any VW part look ups online for 2006 it shows KN or KM manual. VW did not make it simple, banging my head. Have you ever noticed and build code tags on existing harnesses?

Just for reference, that other thread is an EGR error related thread here: https://forums.tdiclub.com/index.php?threads/new-engine-harness-vs-egr-delete.414205/

Plot thickens. When I use parts.vw.com with my VIN it does not show a DSG harness. That same site refers me to the local dealership. Calling the parts counter at the dealership, with my VIN it comes up as a DH; he shows he has one in Canada 7-10 days at $503. Dropping that PN into parts.vw.com without the VIN/Model/Year with pickup at the same dealership comes up at $343. I am now 90% sure I need the DH but afraid to pull the trigger until I am ready to wrench.

For entertainment purposes when I first called he gave me a very different part number for the engine harness, that once I googled, was a full body harness at $7k, then when I got this 03G-972-619-DH number he insisted it was a transmission harness. Fun times.

And it seems like I found the VIN split in ETKA is not accurate, which is not anything new. There are lots of mistakes. I'm sure any tag on the harness in your car is long gone.

If a dealer ordered something for your car by VIN, and it was wrong, that dealer should be taking it back. Simple as that. Ours would, but we also order a crap ass ton of parts from them, too.

I went ahead and ordered the DH at the local dealer but through parts.vw so we will see if they get the one from Canada or if it holds it up. I did make progress on the Smyth build over the weekend so it is almost a drivable project again, so I may get to the engine sooner. I will get the water neck ordered too and the sensor o-ring, I saw those on your recommendation list.

Well just a very long awaited follow up after some shoulder surgery, rehab, and a lot of procrastinating because I knew the job would suck.

The DH harness was a direct fit, I installed it yesterday and wrapped stuff up this morning. Afterward install I was getting a boost pressure error that I traced to a split vacuum hose, hopefully that fixes that. I will start driving the car, er truck, regularly to see if any gremlins come back or if this resolved things like the sensors that would go to "too much resistance" faults.

Much thanks to Oilhammer for the tips on these forums. If you can do this job in 4 hours you are awesome, 2 hours you are a god, I probably donated 6-7 hours to the swap. I of course had the typical wiper blade fight (I need a smaller puller). There was a bunch of engine oil in the connector under the air filter presumptively from the mess in the air filter when I bought the car and old turbo hemorrhaging. It must have been draining out of the box and into the harness connector. I also had to do some other wire repairs at the connection to the relay under the fuse box where the glow plug wires go. Otherwise taking my time to remove part of the old harness while I installed part of the new one clip by clip to ensure OEM routing.

Without your tips I would have been lost on the CPS, mine was packed with sludge from valve cover oil leak which was also previously fixed. After removing the oil pressure sensor and cleaning the area, I could see the clip. I didn't have a pick long enough, so a wire coat hanger with a very small hook bent into the end worked better for me to pull on the release while pushing with the screwdriver.

I have a new DF harness here if anyone is looking for one. I replaced mine in my 06 manual last spring and it seems to have fixed my intermittent shut off problem. I don't think I'm awesome, but I don't think it took me more or not much more than four hours. I did a little video on it.

Well I think you're awesome!

(hey, you saved a TDI and fixed what ails it!)

Actually I'm happy that there were still some new harnesses out there to fix them.