My TDI has had intermittent glow plug light issues - no lights come on, so car will crank but won't start. Thought glow plug relay was going bad, easy fix, so did that. Worked fine for a few days, then started up doing the same thing again. Now no glow plug light, car cranks but acts like getting no fuel or spark. Have checked glow plugs - all good. Good voltage on battery. Tried OBDII scanner, but won't link up with ECM. Have no clue where to go next. Please help!
I don't have the solution but a possible help in diagnosing. If you remove the water temperature sensor connector from the sensor, the glow plug light should stay on when you go to start the car. Try leaving it on for 15 seconds and then start the car. If it starts right away, it is your sensor. If it doesn't, the good luck.
The sensor is located on the right side of the engine near the top, at the back. It is in the coolant fitting directly behind the hose from the rad, just left of the thermostat. Be careful to disconnect the wires, and not remove the sensor, or you will loose a lot of coolant. The sensor is held in by a separate plastic clip, and the harness just has a little built in clip on the side. Hope you have small hands...
Thanks for all the pointers. The issue turned out to be a corroded wire which connects the Power Relay's primary circuit to the ECM. So symptoms appeared to be a bad power Relay. When I bench tested the power relay and realized it was OK, knew there was an issue with the primary circuit. tested voltage and was low (approx 6V) available to connector 86 on the relay; so definite drop somewhere.
Using Bentley diagram, I traced wire back from Power relay to position on ECM and sure enough there was a pinhole in the wire's plastic casing. Plastic casing appears to have rubbed against the ECM housing creating a small pinhole allowing moisture in. The wire was 95% corroded, and hanging together with a couple wire strands! Cut out the bad section of wire and resoldered and everything working again as it should.
Thanks for the help!
alayden
My problem was the ECM ( computer). Most often this problem is caused by the 109 relay, a much cheaper part.
Very common problem in our shop. I bet you it is the main power relay located under the dash on the driver's side. That relay failure is consistent with your symptoms.
Hi, You'll both find the best way is to get the fault codes read, using VAG-com, and once armed with them start Googling or go to http://www.bentleypublishers.com/tech/vw/vw.dtc.table.htm
where you'll get some pointers. D
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have the same problem on my 806 changed 12v heater relay ran wire straight to battery still same problem will crank but wont start unless i get out and move relay then it clicks and glow plug light comes on and will start checked all wires seems ok what can it be?
same problem on 1998 VW polo
no glow plug light - taken to VW garage for diagnostic - they changed temperature sensor and problem fixed for 2 weeks. Then started again so i took it back and complained and they changed the relay. again fixed for 2 weeks, started again so I took it back again and complained again and they changed the control unit. The problem has started again but I'm not taking it back to that garage again as they don't seem to have a clue. The garage should have run a diagnostic . . .
I have a very similar problem on my 99 Jetta TDI.....The glow light on the dash is not lit, but everything else is normal.My glow light illuminates each time I start the car regardless of the temperature ( I am located in eastern Ontario, Canada) I connect my ODBII reader and get "error" indicating cannot read; (have successfully pulled codes from this car in the past). I just rolled the odometer over @ 300K and suspected some sort of factory relay set to fire at that mark!!! However I have heard runors of the power relays so will disregard my conspiracy theory for now and check the power relay first..
Exactly the same problem, no light, no start. In addition the car stalled 3 times at highway speeds. After pulling over to the side of the road I was lucky enough to have the glowplug light mysteriously come back on after 5 or 6 minutes, whola the car starts again.
I replaced all the filters, checked for water in the line and replaced the main power relay. I went out this AM to move the car, no glowplug light, no start.
I have a 1999.5 A4 Jetta TDI which is mostly the same as the 2000 model.
glow plug light flashing and car not starting
starter replaced. Now will crank, but engine will not turn over.Glow plug light stays on and thre is a clicking sund in the fuse box
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