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
The 2002 ALH engine in my Vanagon needed a new Glow Plug Harness. It was throwing DTCs as well as being all brittle and falling apart. It is a 4-wire GP Harness with a long pig-tail having a 4-Pin Connector.
So, here is the stupid mistake I made. I crawled under the Van out in the drive-way and proceeded to find a 4-Pin Connector. Wow! I found one. I promptly unplugged and plugged in the new GP Harness.
Damn. Why did VW make two different sets of circuits that have Connectors that can be plugged together? The long pigtail should have prompted me to question what I was about to do. Yes, I should have spliced-in the GP Harness at the engine and been done with it.
So, I mistakenly plugged the GP Harness to the connector that contains the DFM circuit from the T121/38 pin at the ECU to the Alternator and the L circuit that's connected to the Cluster at T32/12 (battery light) as well as the AC Positive for the coil from the On switch (Temp Control dial of the Vanagon AC system) and Ground for the AC coil.
Those circuits would have been Connected to the Glow Plugs. (Don't confuse this to mean the above got voltage from the GP relay.)
In the Connector
#1 - goes to the DFM circuit on the Alternator from the ECU at T121/38. This circuit allows the ECU to monitor Alternator output which is utilized to maintain engine speed as more current is drawn when things are turned On such as lights, AC, radio, wipers, signal lights, brake lights, tail lights, etc.
#2 - goes to the Alternator at L which is from the Cluster at T32/12 for the Battery Light Symbol
#3 - goes to the AC Coil for Positive
#4 - goes to the AC Coil for a Ground
So, now, with everything plugged correctly, the Battery Light Goes out when the engine is started, but the ALT doesn't seem to be charging. VCDS shows 11.55 Volts with the engine idling. Adding a 12 Volt Charger set on 2amps will only raise the voltage up to 11.63.
The engine starts fine. The accelerator is responsive. The only DTCs are the codes for the 4-GPs because the harness was cut-off at the engine.
The Alternator and AC Compressor could not have been damaged because they were obviously unplugged.
The only thing I can see that may be "screwed" is the ECU, circuit #1 in the above. But, since Circuit #1 is a signal (150Hz) to the ECU, a Glow Plug couldn't send such a signal.
Thoughts!
So, here is the stupid mistake I made. I crawled under the Van out in the drive-way and proceeded to find a 4-Pin Connector. Wow! I found one. I promptly unplugged and plugged in the new GP Harness.
Damn. Why did VW make two different sets of circuits that have Connectors that can be plugged together? The long pigtail should have prompted me to question what I was about to do. Yes, I should have spliced-in the GP Harness at the engine and been done with it.
So, I mistakenly plugged the GP Harness to the connector that contains the DFM circuit from the T121/38 pin at the ECU to the Alternator and the L circuit that's connected to the Cluster at T32/12 (battery light) as well as the AC Positive for the coil from the On switch (Temp Control dial of the Vanagon AC system) and Ground for the AC coil.
Those circuits would have been Connected to the Glow Plugs. (Don't confuse this to mean the above got voltage from the GP relay.)
In the Connector
#1 - goes to the DFM circuit on the Alternator from the ECU at T121/38. This circuit allows the ECU to monitor Alternator output which is utilized to maintain engine speed as more current is drawn when things are turned On such as lights, AC, radio, wipers, signal lights, brake lights, tail lights, etc.
#2 - goes to the Alternator at L which is from the Cluster at T32/12 for the Battery Light Symbol
#3 - goes to the AC Coil for Positive
#4 - goes to the AC Coil for a Ground
So, now, with everything plugged correctly, the Battery Light Goes out when the engine is started, but the ALT doesn't seem to be charging. VCDS shows 11.55 Volts with the engine idling. Adding a 12 Volt Charger set on 2amps will only raise the voltage up to 11.63.
The engine starts fine. The accelerator is responsive. The only DTCs are the codes for the 4-GPs because the harness was cut-off at the engine.
The Alternator and AC Compressor could not have been damaged because they were obviously unplugged.
The only thing I can see that may be "screwed" is the ECU, circuit #1 in the above. But, since Circuit #1 is a signal (150Hz) to the ECU, a Glow Plug couldn't send such a signal.
Thoughts!
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