Funny Story

[Crazy Dazz]

My son and I bought a Jeep Cherokee at Auction last week.
(Down the track he is very keen on a I6 transplant, but that’s another story.)
Couldn’t get the bugger started. Cranked fine, plenty of fuel (judging by the smell) but no spark.
Discovered it was fitted with an immobiliser. Took some research and emails to identify it, and got a wiring diagram. Used a good quality copper wire to bridge the immobilised circuits. Nada.
Research on the net indicated that the Crank position sensor is often a culprit, so tested it but seemed ok. Tested the coil, seems ok.
Tested the distributor pulse signal, seems ok. Downloaded the complete FSM, which answered a few questions, but still no spark.
Basically narrowed it down to no ground signal coming from the ECM. This is the circuit that was immobilised, so we bypassed the immobiliser circuit altogether. Nada.
So after more than a week, hours of research, and testing anything and everything multiple times, we were at our wits end…
Just doing some mundane resistance testing to ensure everything was still connected, and to ensure that a signal could get from the ECM to the coil. Didn’t work.
This didn’t make any sense! We re-tested A to B, fine. Re-tested C to D, fine. B and C are wrapped together by aforementioned copper wire, so naturally A is connected to D? Nup.
In desperation tried testing the copper wire… WTF?!
It appear the copper wire is sealed or varnished in some way (presumably for use in coils.) It’s impossible to see, but the wire’s surface has zero conductivity.
Used some regular copper wire to replace the very first bridge, and bingo. Runs like a charm.