electric problem glow plugs, alt flickering action [Solved]

[Golf/Jetta]

1997 Jetta 1.9L TD w/AC
I've been having an electrical problem.
Starter would not stay engaged but this is not my problem that I'm concerned about.
Alternator is new as of beginning of the winter 2010.
This spring, things have gotten worse.
Before engine Start-Up: On glow plug cycle; the odometer reading and clock would dim down to almost nothing. As if some things are robbing the power (glow plugs).
Once engine has started: the glow plug and glow plug relay would flashes/stutter/flicker with the alternator (terminal W). The faster you rev the more flicking there is. If I take the glow plug relay out, the glow plug light still flickers with the alternator.
After engine warm up: revving beyond 3000 RPMS would stutter the tach back down to zero.
Things I did;
Took apart the instrument cluster, checked for bad solder joints. Result, nothing has changed accept I fixed the airbag light from coming on. (it was a bad solder joint not making connection)
Replaced the instrument cluster with a gas cluster: result, nothing has changed. (engine light still flickering)
Hotwired the ignition switch: result, no change
Switched alternators, I could go beyond 3000 RPMS and the tach would not stutter. Nothing else changed.
Switched batteries: result, no change
Took apart the fuse and relay panel apart, looking for corrosion. Result, no corrosion, no change.
Disconnected each electrical socket behind the fuse and relay panel, one by one: result, nothing.
Cleaned all grounds and positive connections: Result, no change
Using booster cables I connected the engine/battery with negative and positive terminal to inside underneath dash. Result, no change.
Disconnected all connections, one by one: result, one made the relay and light on dash for the glow plugs start flickering was disconnecting the temps sensor on the engine block. This was after the engine warmed up a bit and the glow plugs were not needed for a second start. Disconnecting the alternators W and D+ terminal stoped the pulsating action.
Oppinion and comments are needed. For an example when I took the glow put relay a part all It had inside was a relay switch and a resistor. Where is the computer for this thing? Does it need to know the RPMS?

Conclusion
During the summer of 2010; when the glow plugs first engage, the odometer reading and clock display would dim down to and nothing until the engine has completely started.
Start date: the end of winter (spring) 2011; When the engine is cold and just warming up, the glow plugs flicker (on off on off, moving with the alternator terminal W, and the pulsating action can be increased with a touch of the fuel pedal). To fix this pulsating action, I completely remove the glow plug relay, but the indicator light on the instrument cluster still pulsates. After engine warmup I am able to put the relay back in without it flickering on off. When driving beyond 3000 RPMS that tax debtors and the glow plugs engage stuttering. When I reach below 3000 RPMS, everything comes back to normal.

[joat]

about the only things that may be happening ....

1 the alt has developed a flat or dirty spot on the slip rings ( or the brushes have worn prematurely ) and make sporadic contact. = pulsing alt dash light

2 this creates low voltage for the car and battery which affects the car computer and running problems.

try starting the car and read the battery voltage with it running ( after it charges the battery back up from starting ) should be above 13.8V at idle and less than 14.4V if my brain hasn't failed me again. if you read 12V or less , the alt is toast.

[DanHoug]

that car may have a main power relay thru which all current flows thru. if so, the relay contacts inside the cube may be burned.

otherwise, you said you cleaned the battery connections but make sure you clean both ends of each cable. and the ground cable may run to the body and then to the transmission. examine the conductor to clamp connection at each end as sometimes these will corrode internally and cause a high resistance connection.

your flickering and subsequent stopping with disconnecting the alternator is saying that the connection to the battery has high resistance so that the battery does not act as a ripple filter - like a capacitor. and the clock/odometer diming when the GPs are on is also a sign of high resistance. suspect your battery cables and ends.

-dan

[Fatmobile]

Yep, battery frame ground.

[Golf/Jetta]

Things I've done
-Disconnected the 5 to 4 wire converter for the trailer hitch; Result, No change
-Inspected control module “136” for bad solder joints/blown caps. $358 CAD for a new one at the Volkswagen dealership.
-Check voltage from alternator/battery: 14.5v on start idle/3000 RPMS

Fixed problem; Ground wire (near coolant flange) on the side of the engine, “coming off the quick disconnect” (2x glow plug, temp sensor, two fuel solenoids, oil pressure sensors) was loose and corroded/dirty.

When I took off the ground wire, the instrument cluster would light up but when you put the ignition in the on position, it wouldn’t even light up. No clock, nothing. Nothing would start up. Not even the starter. How convenient. Ignition ON; When I took the ground wire and connect it to the negative battery post, it caused a spark when it touched. After all the ground locations, checked and rechecked how could I miss this one.

After Fix; Checked RPM range; Result: normal


Thanks to all that left a comment and opinion. You motivated me in my quest to find a solution.
But a great thanks to Tim that was the first to tell me it was a ground issue.