85 Jetta Diesel Starting Problem (Electrical?)

Hi occasionally but happening more frequently when I turn the key from run (warming glowplugs) to start nothing happens. After multiple attempts of resetting the key and trying again it works. At first I though it had something to to with a safty switch on the cluch because it appeared to work when I would press harder on the cluch or release and repress the clutch down but then discovered the starter will crank even if the cluch is not engaged.

Any suggestions? My next step is to have a jumper wire ready for the next time it happens and attempt to leave the key in the run position and apply power to the solenoid with the jumper and see if it cranks over.

Thanks for any and all help

PS my jetta has 340k miles and going strong (well strong enough)

~ Phil

That would help determine if it's the starter or not. If it does crank with a jumper wire you will have to decide if you want to replace the ignition switch or add a booster relay to the circuit.

?? Booster relay circuit, do you mean just wire in a switch into the car to the starter solenoid?

THanks

~ Phil

No, if you are getting voltage through the start circuit to the starter solenoid, but it won't crank (& as you stated if you put a jumper wire to the solenoid it does crank) then there is an amperage problem, common on VW's. A common fix (even a recall performed by VW on some models) was to insert a relay into the circuit near the starter. Basically they would take the existing starter wire from the switch & use it to activate a 40 Amp relay that just connected from the battery directly to the starter.

Check the ignition wire to the starter solenoid, that sometimes gets loose.

I had that problem.

Sorry for the delay and thanks for the suggestions. Using a jumper wire I was able to start the car so I put in a momentary on switch in the car connected to the solenoid and it goes to the battery with a fuse inline and now it starts fine with that.

Thanks

~ PHil

Dear Phil,

I also have a starter problem. Jetta 1985 diesel.
You mentioned a jumper wire. Please tell me what you jumpered to what terminal of the battery.

Thanks,
Tom

It sounds like he ran a wire from the battery positive, to a switch on his dash, then on to where the small red/black wire plugs onto the starter solenoid.

before you do that- check the fuse box. A lot of times the wires right behind the fuse box come lose or get crimped. moving the clutch pedal could inadvertenly move the wires or relays enough. But sounds like the key switch if it starts sometimes.

for all those who want to start their diesel manually put a wire or piece of metal (2 inches) between the small connection and the large connection on your starter solenoid. if you have an electrical issue (not glowplug related) that makes your ignition switch not turn on the engine will turn over but wont run. simply cut the wire going to the mechanical fuel pump and put the end from the pump directly to the battery, that will allow the fuel to flow. to shut of the car remove the wire from the battery.

i have a 1984 vw rabbit diesel 1.6 liter. one day i started it up and went to turn on the lights and they turned on for a split second then the the whole car shut down. there was no response from the ignition switch whatsoever. neither was there any response from the light switch but the brake lights and the hazards still work. there were no blown fuses. the underhood fusible link was not blown. the next day i figured out how to jump the starter and got it to turn over then i jumped the mechanical fuel pump and started it up after manually connecting the glow plugs for about ten seconds. and drove it home without any lights of any kind. i slaved in a new ignition switch and that didnt fix the problem. can anyone help.