Dead Motronic Spider, more info

["Rich Hirsch" <rhirsch@xxxxxxxxxxxx>]

Hi Guys,

To recap, a friend's '90 Motronic Spider won't start. The fuel pump is not
running while the engine is cranking and there is NO spark.

Since I posted yesterday, I did the following:

1) I tried to get any fault codes out of the ECU by turning key to "on" and
pressing big red button near the ECU.
No response from the "Check Eng." light. Info I have says the engine should
be at 2000 rpm when button is
pressed to recover codes. Since I have a no-start condition, this is
impossible. I assume I should
still be seeing codes and I am not. (Thanks for the diagnostic info Ralph!)

2) Power to ECU. Pin 1 has +12v with key OFF and ECU disconnected. No other
pin is live.

3) RPM sensor is oil soaked, but looks OK. The first connector was opened
and is very clean.
Resistance between pins 2-3 is 500 ohm. Couldn't find any info on checking
device other than with
a scope and I'm ready to do that yet.

4) In desperation I checked all four relays near the ECU for continuity and
closure (BTW there are NO
fuses in this area that I could find). One of the relays had an open coil.
It is the relay closest to the
big red button (BRB) and I don't know what this relay does. Does anyone
know? It has a top-mounted
15a fuse. (It is NOT the fuel pump relay, which is furthest away from the
BRB.) So I'll replace it and
hope this will restore operation of the fuel pump and spark. (BTW I took the
relay apart and it has
no obvious burn marks or discoloration.)

I've ordered a CarDisc for this car that will hopefully tell me what some of
these relays are for,
and provide a wiring diagram and useful troubleshooting guide.

Thanks to all! I'll let you know if the new relay solves the problem.

Rich Hirsch
St Louis MO
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