Symptom is starter does not engage. Starter (recently rebuilt, new solenoid, etc.) works when jumpering pin 50 on the starter to +12 volts.
Applying +12 volts to pin 50 on the back of the ignition does not engage starter, leading me to believe it is not the ignition switch. FWSM schematic shows Relay XIV with a jumper to pin 50. When I apply +12 volts to the jumper nothing happens (with key on). Is there anything more to this circuit? (i.e. "shut up and replace the ignition switch"!)

Charles - perplexed in NH, but glad there are two companies with 928 in their names. IF only I could drive there to get parts!

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you didn't say what year you have, but here's a guess. there's a black connector right at the jump post, if it's disconnected you have no connection to the starter.

it got me too.

dave

David R. Hendrickson
'88 S4 AT Silver Metallic

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Thanks for the replies.

Shame on me! Car is an '80 Euro S with a 5 speed. There is a jumper where the "Starter Blocking Relay"(Relay XIV) would be. When I jumper this jumper
with a 12 gauge wire to + 12 volts the starter engages. I measure 0.4 ohms from the ignition switch connector, pin 50 to the starter solenoid trigger
on the starter. (I have cleaned and greased the connector by the jump-start terminal. It looked ok.) I disassembled the ignition switch and cleaned the
arced contacts. It now functions sometimes. What disturbs me is that when I use the same 12 gauge jumper at the ignition switch connector, pin 30 (both pin 30s, simultaneously) to pin 50, many times the solenoid merely clicks.
Exactly the same symptom that caused me to get the starter rebuilt. (The brushes were almost gone, but the rebuild dude said there was nothing wrong with it.) Battery voltage is 12.8 volts. Does this mean there is something funky with the ignition switch connector? I measured 9.2 Amps to energize
the solenoid, jumpering it with an ammeter from the starter hot terminal. That seems like a lot of current for an ignition switch to handle, particularly over a 20+ year life...

Charles in NH - 80 928S with a MTBF of 1 day, MTTR of 3 days...

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At 03:32 PM 7/9/2003, charles wrote:
>Thanks for the replies.
>
>Shame on me! Car is an '80 Euro S with a 5 speed. There is a jumper where the "Starter Blocking Relay"(Relay XIV) would be.

This eliminates any possibility of problems with the transmission switch and the relay. Doesn't eliminate possible high-resistance problems at the relay socket connections, though.

>When I jumper this jumper with a 12 gauge wire to + 12 volts the starter engages.

This eliminates possible problems from the relay socket to the starter solenoid, including the jump start terminal connectors and the O plug at the bottom of the power panel.

>I measure 0.4 ohms from the ignition switch connector, pin 50 to the starter solenoid trigger on the starter. (I have cleaned and greased the connector by the jump-start terminal. It looked ok.)

While 0.4 Ohms wouldn't be good as circuit resistance (it would be a 3.6 volt drop), it is fine in this case - what you are measuring is the resistance of the start valve and the thermoswitch that are also fed by the yellow wire.

>I disassembled the ignition switch and cleaned the arced contacts. It now functions sometimes. What disturbs me is that when I use the same 12 gauge jumper at the ignition switch connector, pin 30 (both pin 30s, simultaneously) to pin 50, many times the solenoid merely clicks. Exactly the same symptom that caused me to get the starter rebuilt. (The brushes were almost gone, but the rebuild dude said there was nothing wrong with it.) Battery voltage is 12.8 volts. Does this mean there is something funky with the ignition switch connector? I measured 9.2 Amps to energize the solenoid, jumpering it with an ammeter from the starter hot terminal. That seems like a lot of current for an ignition switch to handle, particularly over a 20+ year life...

It isn't unusual to have a problem with the ignition switch. The electrical portion may be replaced separately from the lock portion.

It is barely possible that there is a problem with the 12 volt supply to the ignition switch. You could check this by using your 12 gage jumper from the 12 volt supply leads at the central power panel to the 50 terminal at the ignition switch. If it works every time, check the connections at A1 and A2. (Lowest and next terminals on the left row of the first plug.)

The power flows from the ignition switch over a yellow wire to terminal A6 - that is, one of the two yellow wires in the second terminal up in the right row on the first plug on the bottom of the central power panel. (The other yellow wires runs to the Central Warning Computer.)

Terminal Connections on the plugs

4 8
3 7
2 6
1 5

Plug A is on the left end, counts up to N, skipping I - that is, i The two short plugs in the center are Y and Z Start counts up again with O up thru X

The three terminals just above Y and Z are battery voltage - bus 30.

Wally Plumley
928 Specialists