2002 Jetta TDI ALH, aftermaket transponder bypass unit wiring horror

[fleuryperformance]

Hi guys,

I just did a complete overhaul of my ALH engine. I've putted it back in the car today. I plugged all of the wires, hoses & sensors at their factory location.

Once I got to the step of plugging in the glow plug wiring harness, I realized that the wires at the other end were cut. I just bought the car, that's why I didn't realize it before. So the previous owner cut the glow plug wire (They are not connected to nothing) and sliced/added two additionnals wires. The first wire goes to the engine speed sensor connector (purple one in the picture at the end) and the second is connected after the blue wire of the old glow plug wiring harness.

I followed these two added wires to the interior of the car and the whole thing is connected to a s**** load of wires then connected to a transponder with a key inside.

My question is the following. I want to put everything back to original. Can I remove the transponder without compromising the operation of the car? I have never seen these systems on any of my vehicles. Also, I would like to know where are the 4 cut wires of the glow plug wiring harness connected to normaly?

Thank you very much for your help.


Pictures :

https://ibb.co/DkDpmf8 (Inside the transponder box)
https://ibb.co/NSw39pX (The transponder box)
https://ibb.co/Hgt3GVy (Yellow wire that are sliced/connected to the BLUE wiring on the old glow plug harness)
https://ibb.co/nDbqgJ8 (Purple wire that are sliced/connected to the engine speed sensor connector)
https://ibb.co/MNZKmCj (The wires that are cut from the glow wiring harness)
https://ibb.co/4KMcYbm (My new motor that I've just built on the last month)

 

[fleuryperformance]

I hope everything is clear, if you need more precision feel free guys. Thanks for the help !

 

[wonneber]

Looks like you are going to have fun.

The " transponder box" was ->probably<- put there to bypass the sensor coil inside the steering column.
Maybe bad sensor, messed up wires or ?

The 4 glow plug wires should be easy to reconnect to the other end that goes to the glow plugs if you have that part.
Salvage yard or new harness if you don't have it.

The yellow wire. Maybe for a glow plug light? I would remove it and tape the wire good.

Purple wire. Tach connector?
Remove & tape.

Last, Nice looking motor motor anyway.

 

[fleuryperformance]

Thanks Wonneber,

However, it's the other end of the glow plug harness that is cut. This is really weird

 

[fleuryperformance]

I just did this little draw to help you to understand where the glow plug wires are cut. I need to know where they are connected normally.

https://ibb.co/Y8nZh4b (Engine bay showing where the glow plug wires are cut)

 

[Genesis]

The wiring plenum is where the plug is for the glow plug harness....

 

[fleuryperformance]

So what connect to the top normaly ? :O

 

[Genesis]

Well if you're going to replace the harness (probably a good idea) to the glow plugs and plug for it is in the plenum. Just take the cover off and you'll see it up toward the top. I ran a piece of small loom when I replaced mine, because un-looming the factory wiring would be a serious pain in the neck, so I just cut it off and both ends and left the abandoned piece in the factory loom.

 

[fleuryperformance]

Thank you Genesis, I was not expecting this kind of work, seem that I don't have the choice. For the transponder, can I remove the key and all the wiring without issues ?

 

[Genesis]

I do not know. If the immobilizer is still there and active (hasn't been tuned out) then the car will not run without it.

 

[wonneber]

The harness is available from ID-Parts.
The one on my 03 JSW went bad just after the warranty ran out.
Was fun replacing it the proper way and not cutting it.

Hmmm.
Thought I posted this yesterday.
Had a post option today as if I just typed it.

 

[fleuryperformance]

Do these ''EURO'' harness work on my USDM Jetta ? I talk to the seller and he did not know if it would work on my car. Otherwise, he said that 2 Canadians buys these without any complains. Just want to be sure.

Thanks

New Genuine VW TDI ALH Euro w manual Trans Engine Wiring Harness 038971627 F for sale | eBay

Find great deals on eBay for New Genuine VW TDI ALH Euro w manual Trans Engine Wiring Harness 038971627 F. Shop with confidence.

www.ebay.ca

 

[mjydrafter]

Do these ''EURO'' harness work on my USDM Jetta ? I talk to the seller and he did not know if it would work on my car. Otherwise, he said that 2 Canadians buys these without any complains. Just want to be sure.

Thanks

New Genuine VW TDI ALH Euro w manual Trans Engine Wiring Harness 038971627 F for sale | eBay

Find great deals on eBay for New Genuine VW TDI ALH Euro w manual Trans Engine Wiring Harness 038971627 F. Shop with confidence.

www.ebay.ca

I think the posters were suggesting the glow plug harness replacement, not the whole engine wiring harness (insert clever comment about maybe being a good idea having worked on a few of these..lol)

On the key hack, the easiest test would be to disconnect it and see if she starts.

Funny aside I've done that exact hack on a couple of '90's Pontiacs way back when. Soldered a spare key under the dash, because of some tiny broken wires in the steering column. Their "transponder" was a simple resister. LOL

 

[BobnOH]

Well the glow plug system is stupd simple. It may be O.K. as is (from picture). The transponder is a bit trickier. Stock set-up wants a device in or near the ignition switch, connected to the cluster and married to your keys.

 

[fleuryperformance]

Guys, I've started my engine for the first time tonight. The motor run flawlessly. But the glow plugs did not work. I've got two code on my OBD scanner that plugs 3 & 4 did not work (can remember what is was). And the glow plug light stay on like 0.5 seconde when I turn the key.

What could it be ?


Thanks for everything !

 

[mjydrafter]

See if you can find a glow plug thread. Test the plugs (I would bet they are okay) and then you can look at the harness. I would bet it's the harness.

IIRC the ALH harness is a 2 wire (each wire controls 2 plugs) so I would guess one of the circuits in your harness has an issue.

 

[fleuryperformance]

Many thanks for all of your help

 

[Tdijarhead]

If this is an 02 I believe that is the first year for the 4 wire harness. Though there might be some early 02’s that still had a 2 wire harness.

If this car is in your garage and the temp is above 40 degrees or so the glow plug light staying on a half second or so is normal. If you’re getting codes for #3 and #4 glow plug then you almost certainly have a 4 wire system. Check how many wires were cut where they come out of the loom next to the glow plugs.

I replaced a glow plug harness on my daughters 03 and there was a plug in, in that snorkel looking plastic loom cover that is beside the brake master cylinder. I pulled the top piece off and unplugged the old and plugged in the new. My other daughters 01 bug required cutting and splicing wires, the 01 has the 2 wire system.

If I recall correctly a two wire system is unable to determine which glow plug is bad and gives a generic bad glow plug code without identifying which cylinder it is.

Very nice looking engine by the way. Wish mine looked as nice.

 

[turbotec]

Pictures :

https://ibb.co/DkDpmf8 (Inside the transponder box)
https://ibb.co/NSw39pX (The transponder box)

I wonder if this transponder box isn’t related to a remote start installation.

 

[fleuryperformance]

If this is an 02 I believe that is the first year for the 4 wire harness. Though there might be some early 02’s that still had a 2 wire harness.

If this car is in your garage and the temp is above 40 degrees or so the glow plug light staying on a half second or so is normal. If you’re getting codes for #3 and #4 glow plug then you almost certainly have a 4 wire system. Check how many wires were cut where they come out of the loom next to the glow plugs.

I replaced a glow plug harness on my daughters 03 and there was a plug in, in that snorkel looking plastic loom cover that is beside the brake master cylinder. I pulled the top piece off and unplugged the old and plugged in the new. My other daughters 01 bug required cutting and splicing wires, the 01 has the 2 wire system.

If I recall correctly a two wire system is unable to determine which glow plug is bad and gives a generic bad glow plug code without identifying which cylinder it is.

Very nice looking engine by the way. Wish mine looked as nice.

Thank you very much ! I confirm that this is a 4 wires harness ! I've ordered a new one that I will be changing soon.

 

[fleuryperformance]

I wonder if this transponder box isn’t related to a remote start installation.

I've removed it tonigh and the car still running. I think the same as you, this could related to a remote starter.

 

[C.Powell]

Recall something about glowplug wiring repair
With glowplug wiring make sure #1 is the one you think it is as the numbering seems reversed (1 is 4, 4 is 1).

 

[fleuryperformance]

Hi guys,

Just to give you news about the glow plugs problem, I've putted a brand new harness yesterday and it did not fix the problem, still have P0673 & P0674 code. Any ideas ?

Thanks !

 

[BobnOH]

You've done the simple resistance test on each plug?

 

[fleuryperformance]

You've done the simple resistance test on each plug?

Yes, and each glow plugs are new from the box. Bosch OEM.

 

[BobnOH]

Has anyone mentioned glow plug codes do not go away on their own? They must be cleared (silly).

 

[fleuryperformance]

Has anyone mentioned glow plug codes do not go away on their own? They must be cleared (silly).

They have been cleared but they always come back when I start the car unfortunatly.

 

[wonneber]

I prefer to test the glow plugs with an amp meter.
Test the amperage to each plug one at a time.
They should all be about the same.

Next, test that power is getting to the plug opening of the harness.
If you disconnect the coolant temp sensor the system will think it's extremely cold and keep the GP power on for several seconds.

There is a 50 amp fuse in the fuse box above the battery that is for the plugs only.

As mentioned above, it is a very simple system.

 

[Rob Mayercik]

Glow plug relay? On an 02, it'd be under the cowl on the driver's side.

Be warned, it's not a mechanical relay, it's some sort of solid state circuit inside, so it likely doesn't 'click'...

 

[fleuryperformance]

Thanks you so much everyone