(Solved) BRM no start no ECM communication

[bc1550]

Howdy,
I have an issue with intermittent stalling and no start. I'm either getting ecm code 1314 or 1100.

I'm chasing the wiring and connections to the ECM and am looking at the relay.

Everything I see (Bently, web searches) has referenced a 458 relay, but I have a 100.

Do I have the wrong relay or is a 100 common too?

Best I can tell, the 458 has what I think is a diode (or some extra connection) and is 40A rated vs the 100 is 70A & no diode.

New item by Bryan C

photos.app.goo.gl

TIA

 

[Nuje]

BRM weird electrical issues? After probably 10hrs of chasing issues and repairing wires here and there that I figured would fix the problem, I took @oilhammer's advice and replaced the engine wiring harness.
Problem(s) fixed.

BRM have a reputation for wiring going bad due to the multitude of tight bends and twists and friction points. And good luck finding where in the wiring bundle the issue is. Might be a a relay, but.....

 

[bc1550]

I took @oilhammer's advice and replaced the engine wiring harness.

Thanks for the input.
However, I have already done the same. My new harness has about 100 miles on it.

 

[bc1550]

After digging around more, it turns out the 100 and 458 relays are interchangeable. It also seems this relay is a somewhat common issue. I couldn't really source the 100 as easily as the 458, so I got a 458 and hoping that's my issue.

 

[borninabus]

have you done any testing on the ignition switch itself?
just a suggestion. good luck

 

[bc1550]

have you done any testing on the ignition switch itself?
just a suggestion. good luck

I didn't really think to, no. Since it was turning on and cranking (but getting no comm errors to ECM), I didn't think the ignition switch would be the culprit. Thank you for the suggestion though.

It's been running well (minus what seems like a turbo issue) for a couple of days, and I just put in a new ECM relay yesterday. So... we'll see.

 

[bc1550]

I edited the title of this thread to see if I can solicit some assistance (rather than resurrecting an old thread).
I don't have the car right now, as it died out of town.

This describes the problem I'm having, but I can't find any info.
No glow light,no start 06 jetta | TDIClub Forums

@Rx7145 asked if the previous person had tach on crank, I do not, but that would be expected as the ECM doesn't seem to be communicating with the rest of the car.

I saw a post about checking reference voltage on a ECM connected sensor to see if the ECM is output voltage. I have not done this yet, but It was stated that if it didn't than the ECM is bad. I'm not sure this is correct since there may be a chance the ECM is not getting power. Thoughts?

This problem is intermittent, so it's hard to troubleshoot, but I believe I tested voltage to the ECM when I had this problem, and it was fine (and not shorted). I will test this again.

I'm getting the car back home next week, but I was hoping I get some more insight on what I could look into.

Thank you.

 

[bc1550]

Well, perhaps someone can help?

I got the car back and tested voltage at the ECM.

Voltage out of relay and fuses: 12.5+-.
Voltage at the ECM: 4.8.

So it's obviously not getting enough power. I pulled apart the wire harness and it is in great shape. The engine harness is new also, but that shouldn't affect this. My thought is that maybe the wire has internal damage or there's a problem with the fuse panel. Any thoughts? How can I test the fuse panel itself?

Edit: grounds are clean too.
Thanks

 

[Rx7145]

I would look at the relay that supplies power to the ECM to make sure the relay is working correctly.

 

[bc1550]

I would look at the relay that supplies power to the ECM to make sure the relay is working correctly.

I have already replaced the relay too, and I am getting 12v past the relay.

 

[bc1550]

I think I know how to test that. I had an idea but spaced it before wrapping the harness back up. Basically, I need to test the voltage at different points on the fuse panel and wire. Voltage Drop Testing ~ The BEST Way To Test Wiring (youtube.com)
Which basically means I need to unwrap the harness again. Sometimes I get ahead of myself...

 

[Rx7145]

Just run a new wire.

 

[bc1550]

Yeah, but if the wire isn't the issue, then I've created failure points that didn't need to be there.

 

[bc1550]

Well, for anyone's future reference, I basically used the technique described in that video above, but I think better demonstrated in the link below to narrow down my issue inside the engine fuse box. As I was testing, the fuse for the ECM (13) was going in and out of showing loss and not. I also heard some arcing with the fuse. So basically, like someone else I've seen, the fuse was loose in the socket. I found a fuse that was a little thicker and bent the legs a little and all is well now.

As mentioned, this guy went into a little more of the technique to narrow down voltage loss. Pretty helpful for me.

 

[325_Guy]

Thanks for posting your resolution!

Ten years from now somebody's gonna find this thread and it'll help them out.

 

[bc1550]

Thanks for posting your resolution!

Ten years from now somebody's gonna find this thread and it'll help them out.

Of course! There are few things I like less than a thread without a resolution (which is so very frequent).