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UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS
Have to get communications with the ECU.

I believe that there's a ground under the ECU.
 

Warthog

Veteran Member
Joined
May 16, 2004
Location
Clemson, SC
TDI
see Bio
Sounds like my problems with "2000 Jetta won't run". See if reading that post helps you.
It still won't run...am still hunting for fix.
 

Warthog

Veteran Member
Joined
May 16, 2004
Location
Clemson, SC
TDI
see Bio
Jump to the fuel solenoid valve directly from the battery and then try cranking. Mine runs when I do this and continues to run when I disconnect the jumper.

At the time of this writing, it continues to crank AND RUN without the jumper...as the VCDS says: "It's an intermittent fault"

I snagged a good 109 relay today but haven't had time to install it in MY car. Maybe tomorrow...I'm also investigating a hot-wire installed from some switched point (#15) to the fuel solenoid valve to bypass the ECU altogether.

I don't recall if you said the starter would work...I may be ahead of what you can do, with the above comments! My starter IS cranking the engine.
 
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UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS
I wouldn't necessarily conclude that the electrical is fine. Sure, it can read OK, but once a real draw is place on it it can deviate enough to cause problems. Think of it like alike the difference between a voltage test and a load test on a battery: voltage might show good, but that doesn't mean the battery has any significant electrons to part with.

As Warthog suggests, jumper the solenoid (making sure, of course, that your battery is good!).
 

Warthog

Veteran Member
Joined
May 16, 2004
Location
Clemson, SC
TDI
see Bio
I replaced my 109 relay and NOW things seem to be OK. Multiple starts and restarts and engine runs each time.

Danny, Even tho you DO have a gray 109, I'd try replacing it...the one I used was from another A4 Jetta but it did do the trick. If you are following my thread, You will see both the ECU communication faults went away after 109 replacement but now I have a fuel shut-off valve fault showing. also intermittent.

Not to mentiion the little laptop computer is being RUDE.

If your 109 is not doing its thing, your ECU will not communicate and your GP light not coming on sort of suggests a power failure thru 109. ( I read THAT in another older post, or maybe it was in a "sticky")
 

Warthog

Veteran Member
Joined
May 16, 2004
Location
Clemson, SC
TDI
see Bio
If you unplug the temp sensor in the coolant line, do the GPs come on?
I'm trying to think of how to bypass things that might be messed-up to check circuits.
You ought to get communication with the ECU when the switch is ON...I do but am using a Ross VCDS...someone with freeware is not having luck with this either.
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS
So, the fuel isn't really spraying out?

What happens if you apply power to the fuel shutoff solenoid and do this?
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Finding water in an injector is not good news!

The ECU controls the Injection Pump when cranking the engine and while it is running (obvious). So, if the IP is loaded with corrosion and/or water, it's not going to function properly or at all!

I'm not sure if VCDS will allow a force delete of codes but Scan Gauge will. It would be good to dump all the codes and start over!

Make sure the positive connections on top of he battery are clean and no blown fuses. The corrosion under the battery will most likely affect the fan functions and AC compressor and not the ECU or OBD function.

The ECU is not grounded on the outside, only through the connectors.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
There's two hot wires to the OBD port. One of them is always hot and the other is hot when the ignition is ON.

What I meant about the ECU grounding, is that there's no direct ground from the outside of the case. Everything is through the connectors.

As for the ECU being fried, if that be true, whatever caused it may still exist.

Couple of points: 1. I purchased an ECU that was laying on the cowl of the car in a Junk Yard. It had water standing in the two connection slots..... however, it was just fine! 2. Back about 4 years ago, when I was doing my ALH in the Vanagon, I accidently let a big hot wire drag across the outside case of the ECU. No problem, as it has served well over 70k miles.

I'd be concerned about the PO's hack job installing the stereo system. He may have cut wires for a power source that involved the OBD port and/or one of the three power wires coming out of the Relay 109 socket.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
..................
I'd be concerned about the PO's hack job installing the stereo system. He may have cut wires for a power source that involved the OBD port and/or one of the three power wires coming out of the Relay 109 socket.
Yes, get a hold of the wiring diagrams for your car and go thru all that stuff near the radio.
 

Warthog

Veteran Member
Joined
May 16, 2004
Location
Clemson, SC
TDI
see Bio
To answer an earlier question, You CAN force clear ALL faults with VCDS.
Outstanding ones come right back.
Ones that you've remedied stay gone.
They don't go away by themselves tho, even when you FiX something. they have to be cleared. (Or maybe start and run engine 30 timeswithout a fault?)
 

abuzar1

Active member
Joined
Oct 6, 2014
Location
Orlando
TDI
B4 Passat
Following this thread too as I've got a no start due to fuel issues cuz of ecu not getting power. Also have aftermarket stereo.
 
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