1991 BMW 318IS No Crank Issue

[Mark92131]

We are having an issue with our newly acquired 1991 BMW 318IS that I have researched without finding a satisfactory course of action. The car seems to be experiencing some kind of heat sink related issue with the starting circuit. When the car is cold, it starts and runs great. The battery is fully charged, the connections are good, the starter spins the motor without any hesitation, and the car starts, runs and idles as expected. After the car has been driven and is up to normal temperatures, it can be stopped and immediately restarted without any issues. However, if the car sits for 20-30 minutes in the heat of day, you can get back in the car, turn the key, the dash lights display as normal, but when turning the key to start, nothing happens. No click of the solenoid, no diming of the dash lights, no crank of the starter, nothing, dead silence. Wait another 20 minutes for the car to continue cooling down, turn the key, car fires up like normal. Something in the starting circuit does not like the heat, but I am not sure where to start. Normally, I would suspect a bad relay, but the manual E30's don't have a starter relay, just "unloading" relays? If anyone has experienced this issue, I would love to hear how they fixed it.

Best regards,


Mark92131

[Dj Buttchug]

Check all of your engine, and starter grounding wires. Make sure they are tight, clean and have a good connection.

[uturn]

Unloading relays turn off lights, etc. so that full power can sent to the starter circuit.

[D3R3K]

i would try replacing the main relay/ starter relay as a starting point

[Mark92131]

Update... I cleaned all the starter connections, battery connections and grounds and would still have the same issue in hot weather, Dead Starter, no solenoid click or motor engagement. I replaced the DME Relay, the issue did not go away. I bought a new, replacement starter and was planning on going through the headache of swapping it out. Had a couple of independent garages quote $400 to $600 for this task. For that kind of money, I could do it myself. My son is taking the 318IS to college in LA at the end of the month and I really need to get this fixed. I was pulling it in the garage to pull the starter and used the key fob to open the doors and disable the alarm. At that moment it hit me, I had an E30 325IS and I don't remember it had a key fob, just a key. This car has an aftermarket alarm system, a K9-Classic-E to be exact. I pulled up the installation manual and there it was, OPTIONAL STARTER INTERRUPT OUTPUT. Turns out there is option for adding a relay that will interrupt the power to the Solenoid if the car is armed and ignition key is turned to the start position. This must be the issue I am having, this relay failing to operate when exposed to high temperatures.

I pulled the under dash panels and found the alarm unit along with a rat's nest of wires, sketchy connections and shoddy work. I traced the "orange" starter interrupt trigger wire to the relay and found a mess at the relay. The PO or installer tried to use a stock 5 pin relay instead of the 3 pin K9-Classic relay designed for Starter Interrupt option. The 5 Pin Relay Socket was modified with a resistor spanning 2 of the sockets and 1 jumper. I ordered the proper 3 pin K9-Classic Relay and bypassed the modified relay completely so I can start the car and test if this fixes the issue.

I'll report back later.

Mark92131

[jsnppp]

I too ripped out the shoddy alarm system in my 318is. About 30 lbs of wire and crappy electronics. I bet you are right and this is it.