Cold starting and Wiring harness faults

BMW Wiring Harness Problems and Faults Cold Starting

Model :
BMW 325e (produced before 10/85)
Complaint:
During low outside temperatures there is no ignition spark, therefore cars cannot be started.
Cause:
The cable on the battery junction block has been installed incorrectly. The battery junction block can be located underneath a black cover on the right hand side when looking forward in the car.
Remedy:
Connect the cable.

Engine Test – Ignition Timing Angle Diagnostic Readout

Model:
BMW M3
Complaint:
The ignition timing angle cannot be read out on some vehicles when performing an engine test. However, the correct functioning of the engine management system is not effected.
Cause:
When the wiring harnesses were produced the three wires in the female plug housing (connector C152) for the TDC position sensor were incorrectly inserted.
Remedy:
Peel back the rubber cap from the female plug and cut the three wires, ensuring the cut is as close to the plug housing as possible. Using a new plug housing (P/N 12 52 1 706 068) and the correct female connectors, insert the wires as follows:
Chamber 1: Yellow wire
Chamber 2: Black wire
Chamber 3: Shielded wire

Ground Strap (between alternator and crankcase)

Model:
BMW M3 (through December 1987 production)
Complaint:
Since January 1988 production in order to connect the alternator to the dipstick guide tube bracket on the crankcase, a new and flexible red strap must be used in place of the original brown, rigid strap. Whenever an BMW M3 produced prior to Jan 1988 is in the workshop, the new strap must be fitted.

Starter Cable

Model:
All BMW 325
Complaint:
The starter cable can rub against the brake booster. All cars produced before January 1986 should be checked in the workshop.
Remedy:
Firstly, disconnect the battery ground cable.
Next, loosen the nut for the starter cable.
Next, Push the cable towards the engine and tighten the nut. Ensuring the cable is against the stop shoulder of the solenoid.
Then, fasten the starter cable to the engine wiring harness with a cable tie.
Finally, reconnect the battery ground cable.

Motronic M1.1 – Circuit Supression

Model:
BMW 528e (1988 model only)
Complaint:
Migrant voltage surges from the ‘Check engine’ light circuit which can effect the M1.1 control unit durability.
Remedy:
Install a suppression diode harness.