97 GTI runs, but will not start

[echman]

I just purchased this GTI knowing that it had a starting system problem.  Previous keeper was 95% sure it was the starter motor (a co-worker, not a scammer).  Needless to say, I've replaced the starter, no help.  Battery is good, two of the three voltage checks were good (the third I was unsure where I was supposed to check).

There is no noise to be heard when I turn the ignition.  We were able to push start it.  The odd part was I got it to start w/o popping the clutch, I actually turned the key.  There has to be a switch or relay that I'm missing somewhere.

At first I thought it had to do with the immobiliser (aftermarket alarm), but now I'm not sure of anything.

I apologize if I"ve left anything out in my haste.  Thanks in advance.

[Ninja]

ECU/Fuel pump relays should be your first point to check/replace.

Second, I would check the crank sensor.

Finally, I would get the ECU earth checked. Water can get under the battery tray, into the wires and corrode/burn the earth.

[javalin]

where have you checked voltages?  At the battery?  At the starter and then at the solanoid whilst trying to start?

Where do you get voltages?

Not the fuel pump or ECU relays - if the car runs when bump started, or the crank sensor, or the ECU earths.  Again as it runs when bumped its just a starting issue.

Could be a ignition switch problem; immob problem or wiring problem to me.

James

[echman]

voltages across the battery are good, as well as voltage to the starter pos lead.  I think the voltage going into the solenoid was bad (also, when I turn the key from run to start, the headlights don't dim, but cut out completely).

The haynes manual fuse/relay box diagram doesn't seem to match my fusebox.  I reseated all the relays and also the ignition switch.  the book shows the #2 position as 'starter inhibitor relay & reversing sensor relay', but I've got nothing in that position.  followed the wires from the switch to the box, nothing obviously wrong.

Here is a pic of my fuse/relay box.

[echman]

My airbag light also stays on, don't yet know if that is legit or just another electrical bug.

[javalin]

have you got good voltage from the engine itself (also gnd) to the batt pos & starter lead?  Wondering about a bad earth cable.

try powering the starter excited directly using a reasonable sized bit of wire.  That would isolate starter issue vs ign switch / wiring.

don't worry about airbag yet.

turn headlights off and fully charge battery first.

oh and what voltage did you get? 12.6+?

james

[Screech16v]

You get ignition lights as normal? but doent crank the engine over in the start position?try wiggling the key when holding it in the start position,sounds like ignition switch issue,very cheap fix if it is

[echman]

I was losing a couple of volts across the earth ground.  Removed and cleaned, no help.

Tried wiggling the key in the ignition during start, fires up no prob.  Of course it's always the last thing you check.

Thanks to all for the help.  Now all I have to do is:

1) source a new ignition switch
2) troubleshoot the airbag light

Thanks again, my blood pressure has gone down just knowing what's wrong.

Orlando

[javalin]

get a new switch from VW.  Good news.

have you solved the loosing volts to gnd?   New cable might be in order.

james

[echman]

get a new switch from VW.  Good news.

have you solved the loosing volts to gnd?   New cable might be in order.

james

finally sourced a new switch, just need to r2 it.  and yes, the volts to ground are good now after a bout with the wire brush.