I have Mercedes 500 SEL (1985). recently engine died on the road. Can
not restart. Here is more details to the problem.
1. Fuel pump does not run with ignition key "ON". It does work when
connected directly (both wires).
2. Fuel pump relay MAKES A CLICK AT THE MOMENT WHEN NEGATIVE CABLE IS
RECONNECTED TO THE BATTERY , with ignition key not in the lock (!?).
3. I found that ignition control module (Bosh) has inside burned
resistor (R 24, which is mounted on the inside of the ICU box). For
that reason the value on the reistor is unreadable. Anyway I found the
detailed circuit for Volvo car with similar engine with value 310 kOm.
After repair engine did not start anyway.
4. One more problem, .RADIO GOES ON ANY TIME I TRY TO TURN AN IGNITION
5. When cranking, distributor sends to the ICU signal about 1,5-3,0 V.
Distributor cup and rotor are new. Ignition wires are new. Ignition
coil was replaced a few Years ago. Fuel pump, fuel filter, fuel
injectors are new. Battrey is brand new . Everything did work
perfectly until now.
Does somebody have any idea if these problems are related to the
possible short or ground in an ignition lock? I found that Volvo
amateurs do this kind of repair almost routinely. Each separate
component for ICU module cost abut 5 Dollars or less, ICU itself even
used at least $115.00.
Thank you for any advice. A.N.