96 Passat wont start all of a sudden

whitedog

Veteran Member
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Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
I agree. Maybe it's not in far enough. Try jumping the connectors at the fuse panel without the relay.

Sorry, I don't know about that ground by the ECU.
 

ToddA1

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Aug 3, 2011
Location
NJ 08002
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'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
That stud in the rain tray is not a ground. It's a mounting stud for the ECU bracket.

That last code would have me cleaning the ground points in the engine bay. Look at the main barrel connector (OOD) at the rear of head, the battery terminals and 2 under the battery.

Clear the codes and try again.

-Todd
 

ToddA1

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Aug 3, 2011
Location
NJ 08002
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'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
Thinking about it, your 109 relay is good. If the ECU wasn't awake, you wouldn't be able to retrieve fault codes.

The cluster grounds are located at the rear of the head. What makes this fun is the bracket is part of the ground path. That's a pain to remove and clean. That bracket then is attached to the head, so those contact points also need to be cleaned.

If you're under the hood and have someone turn the key to the on position are you hearing the stop solenoid and QA click?

When you crank the engine are you seeing smoke at the tailpipe indicating fuel is pumping?

-Todd
 

abuzar1

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Oct 6, 2014
Location
Orlando
TDI
B4 Passat
I'll try cleaning the grounds and I'll see what happens. I'll have someone crank the car for me and I'll record to show you guys the fuel solenoid clicking on and off.

Is there a way to temporarily make a ground with jumper cables? If I were to put the cables on the negative terminal to the block would it bypass the bad ground problem just to see if thats the problem?
 

Abacus

That helpful B4 guy
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Nov 10, 2007
Location
Relocated from Maine to Dewey, AZ
TDI
Only the B4V left
Todd is right, that's an ECU mounting stud, not a ground.

I have seen issues with no glow plug light before, one was the chips in the ECU becoming unsocketed like Dave mentioned, and the other was the wiring harness chafing through. I have had it chafe through on the right side of the car in the engine bay but it was not visible when looking at it. I only found it after running my hands over the entire wiring harness and twisting it so I could see the backside. It was then I found the chafe, and I've seen lots of similar problems on these cars over the years. It's amazing what vibrations and time can do, and it's accelerated when people remove the wire mounts that secure the harness from moving around.

These were from 3 different cars.





 

ToddA1

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Aug 3, 2011
Location
NJ 08002
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'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
I've recently had a cluster ground issue and tried the jumper wires to battery and it didn't help me. A week later on the other B4, I had a starter issue. Jumper wire did nothing.

I removed and aggressively cleaned everything and the issues were fixed. I'm guessing there was too much oxidation that was hindering conductivity, although the contact points looked ok.

No harm in trying, though.

As Abacus mentioned look for broken wires. It could be as simple as that.

-Todd
 

abuzar1

Active member
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Oct 6, 2014
Location
Orlando
TDI
B4 Passat
This is what my cable looks like along with the ground. Main ground looks pretty shiny. Also pics of the ECU. Will clean aggressively and reinstall and see what happens tomorrow.




 

abuzar1

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Oct 6, 2014
Location
Orlando
TDI
B4 Passat
Hey guys its been over a year and the car has just been sitting. I decided to try to do something about it.

I took a multimeter set it to the 2v DC position. Then I put the black pin to ground and the red pin into the ECU connector (ECU was out). A lot of the pins were getting .003 volts, is that normal? Pin 53 had no power what so ever.
 

abuzar1

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Location
Orlando
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B4 Passat
A lot of pins were getting .003 volts and some were getting 11 something volts. Many others less. Are they all supposed to get 12v?
 

abuzar1

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Location
Orlando
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B4 Passat
This is a bit beyond me but I'm trying to learn. I was hoping by testing the voltage on the plug I could see which wire was not getting power then I could trace it back and see if there is a short, or some other issue.

If they are all not supposed to have power with the ECU out, is there a way I can tell which wire is faulty with a multi meter or is physical inspection the only way?
 

whitedog

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Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
There should only be a few wires that have 12 volts when the ECU is unplugged. To figure out which ones, you will need to look at a wiring diagram.
 

ToddA1

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Aug 3, 2011
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NJ 08002
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'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
I'm not going to read through the thread again, but list the troubleshooting steps, you've taken.

-Todd
 

abuzar1

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Oct 6, 2014
Location
Orlando
TDI
B4 Passat
My car stopped working after parking overnight. The check engine light and glow plug light do not come on. When I added fuel (starting fluid) it was starting. I have replaced ignition switch and relay 109(2 different ones). I have also tried a replacement ecu. I have cleaned any grounds that I could find. I have also tried jumping relay 109.

I just tried the multimeter on the ecu plug to see which wires were getting voltage. The only wire that had absolutely nothing was pin 53 from what I see online has something to do with relay 109.

The only other electric issue I had with this car prior to all this was that the left tail light fuse would burn out as soon as you put it in.
 

abuzar1

Active member
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Oct 6, 2014
Location
Orlando
TDI
B4 Passat
The B4 doesn't have an electric fuel pump right? It has a mechanical injection pump driven by the engine? My problem is no fuel, so the issue must be something electrical stopping the fuel from getting to the engine? I did try jumping the stop fuel solenoid but that didn't help.
 

abuzar1

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Oct 6, 2014
Location
Orlando
TDI
B4 Passat
I cracked the fuel lines to be sure and there is no fuel. Whenever I supply voltage to the fuel solenoid wire the car refuses to crank. If I apply voltage while someone is cranking it, it stops. I'm gonna remove the plunger from the fuel solenoid just to see if it will start the car.
 
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KLXD

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Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
I did read through the whole thread.

You're last post is really strange. Applying power to the solenoid shouldn't affect cranking. You sure you weren't grounding it? I wouldn't think even grounding it would cause that. I thought the starting circuit was independent from the electronics.

No fuel may be the problem but it could be caused by a lot of things. Some having nothing to do with the electronics.

When you turn the key on the pump makes a several noises. The quantity adjuster makes a full or nearly full sweep and goes back to zero or some low setting. This is two clicks. The cutoff solenoid picking up is much quieter.

After you pull the guts out of the solenoid let us know what you are hearing. Leave it out until you get this figgered out.

Did you look over the harnesses carefully for chafing as was suggested?
 

whitedog

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2004 Jetta that I fill by myself
The only way I can imagine putting power to the shut off solenoid would stop the engine from cranking is if there is chafed wired putting power to the ground side of the start relay. With power on both sides of the relay solenoid, the relay would disengage since there is no potential across the solenoid.

There is probably other places that could be getting shorted to power as well, but I would have to check my diagrams.
 

KLXD

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Joined
Aug 22, 2009
Location
Lompoc, CA
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'98, '2 Jettas
But if there were such a short, the ECU putting power to the fuel solenoid would do the same thing???

It was suggested back a ways that he check for chafed wires. No indication that he's done so that I recall.
 

whitedog

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Jul 12, 2004
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Bend, Oregon
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2004 Jetta that I fill by myself
If the solenoid has power from a short on the ground side of the relay solenoid and ECU power on the other side of the relay solenoid, the solenoid won't activate. Of course, I don't remember if the ECU switches power or ground, but the theory remains that a solenoid with power on each side won't activate.
 

vanbcguy

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'93 Passat - AHU mTDI with GTB1756VK
The shutoff solenoid grounds through the pump body, which grounds through the mounting bracket, which is directly connected to the engine block. Little possibility of getting 12V there!

I definitely would be looking for wiring problems too based on the symptoms. I doubt the shutoff solenoid is involved.

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whitedog

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The shutoff solenoid grounds through the pump body, which grounds through the mounting bracket, which is directly connected to the engine block. Little possibility of getting 12V there!

I definitely would be looking for wiring problems too based on the symptoms. I doubt the shutoff solenoid is involved.

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I was talking about the start relay solenoid.
 

vanbcguy

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'93 Passat - AHU mTDI with GTB1756VK
Ok - the start relay solenoid grounds through the starter body which is in turn bolted to the transmission and engine block, little possibility of getting 12V there!

Now, if the main engine ground to the battery is disconnected all bets are off.

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whitedog

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Bend, Oregon
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2004 Jetta that I fill by myself
Is there a relay controlling the starter solenoid? Like up in the relay panel? That is the one I am talking about.
 

vanbcguy

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No, the solenoid itself is the relay. The ignition switch is connected to it.

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abuzar1

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Oct 6, 2014
Location
Orlando
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B4 Passat
Alright so I took the plunger out and the car wouldn't crank. I figured the plunger was what grounded the wire so I connected the little wire on top of the solenoid to ground and she started! Starts runs turns off exactly like it should now.
 

KLXD

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Joined
Aug 22, 2009
Location
Lompoc, CA
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'98, '2 Jettas
You've got some weird stuff going on.

The plunger itself has no electrical contact.

The solenoid wire should not be grounded. It should be on the solenoid coil which should have some resistance. Just guessing but maybe 100ish Ohms to ground. Now you're shorting it which I would think would put too high a load on the ECU and burn it out.

Earlier you applied power to that wire and nothing worked which should not happen. Losta guys do that for various reasons during troubleshooting.

Only thing that makes any kind of sense to me is you have a bad ground somewhere and grounding that wire is somehow providing a substitute ground.
 
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