Funny Story

Crazy Dazz · 27-11-2010, 02:49 AM

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.

chrisfpv · 27-11-2010, 11:12 AM

omg so funny!!!!

Tiapan · 27-11-2010, 03:05 PM

haha where did you get the copper wire from? normally the varnish is for motor windings or small transformers haha nice bit of fault finding, i bet you were proud of yourself

**Falcon Coupe** · 27-11-2010, 03:13 PM

How frustrating, you have more patience than I do.

**GasoLane** · 27-11-2010, 03:43 PM

Well done working it out, but didn't you try to start it before you bid on it?

sprint347dave · 27-11-2010, 03:59 PM

good on you for finally finding out what wrong,,but remind me to never ask for you help if im tring to steal a car with an immobiliser

TheInterceptor · 27-11-2010, 07:00 PM

Nice, i admire your patience. I probobly would have ripped the motor out and put in that I6 already.

Crazy Dazz · 27-11-2010, 07:18 PM

My son picked up a big roll of this wire when someone was throwing it out.
Car was bought at damaged car auction, but I’m actually very impressed with its condition. We assumed the engine would be rooted, but it runs well, no smoke and heaps of power.
And yeah, when it comes to immobilisers, I must be the world’s slowest car thief.

JimNiki · 27-11-2010, 07:44 PM

all experiences are good experiences (as long as you survive them of course!)
just put this down to a free lesson for the rest of us ...thank you.

bigsta · 27-11-2010, 10:40 PM

its always the simple things we overlook

How much did you get it for? year?

Till_Lind · 28-11-2010, 02:02 AM

Haha, I can imagine the jubilation when it cranked.

Crazy Dazz · 29-11-2010, 03:53 PM

Quote:

Originally Posted by bigsta

How much did you get it for? year?

It was built in 96, has 97 Aussie Compliance, and is actually MY97.
About $2k all up, which is a bargain in WA.
Really impressed with the engine, he's just not looking forward to the fuel bills.
Hence future plans for the AU engine.