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Damned factory immobiliser

A

alex673

NAXJA Forum User
Location
Western Australia
Hi Guys,

I have a RHD 95 cherokee classic and live in Australia. It's been a good jeep until last night when it decided not to fire up. I had a mobile mechanic come out and he said the immobiliser has stopped the distributor from firing... He checked plugs, points, battery etc... All the usual suspects...

I understand the immobiliser works off the computer, but I was wondering if there is a safe way to disable it? AAARRRGGGHHHHH!

Any advice appreciated.

Alex!!!1
 
Last edited:
Never heard of an "immobiliser", unless that's some kind of weird way to refer to the NSS, the Neutral Safety Switch. (Actually it sounds more like a weird way to say he doesn't know much about jeeps, but I'll try not to say that.)

If the NSS is your problem, yes there are ways to circumvent it, and no they're not really safe (start in any gear) but it's something you can live with for short periods. There are also ways to fix it. Search on that term, the problem has been covered extensively here.

The only "immobiliser" I know of on my jeep is when my girlfriend overhears me making plans and starts off with "So you think you're going out in the woods AGAIN this weekend..."
 
Sentry Key Engine Immobilizer - didnt start til 1998.

I doubt you have one. Even if you use the wrong key, it fires up, but then kills the engine within 6 seconds. It doesnt completely prevent you from starting the vehicle.

Can you put it in Neutral and try to start it?
 
Whoa....I just got a weird case of deja vu....

Anyway, if your key is grey (the plastic part) you have the immobilizer...if its black, you don't. The grey keys are the ones with a little chip built into it.

EDIT: I'll probably get :flame: for posting a link from jeepforum, but it came up when I Google searched :D

http://www.jeepforum.com/forum/showthread.php?t=530656
 
Yeah sorry guys, over here we call the cut-out part of the security system an immobiliser... Damn aussie vernacular!

The problem appeared to be in the engine cut out, but I have since done some diagnostics, and it now appears to be lack of spark from the coil. I'm sorry for the confusion anyway.

Guess I gotta get an auto electrician over to check it out.

Cheers

alex
 
Dave41079 said:
Check to see if your injectors are firing, if not then it's likely a CPS failure, or the coil pickup.
Click to expand...

usually cps failure will not stop fuel pressure--it will just turn over with no fire and never start.
 
alex673 said:
Hi Guys,

I have a RHD 95 cherokee classic and live in Australia. It's been a good jeep until last night when it decided not to fire up. I had a mobile mechanic come out and he said the immobiliser has stopped the distributor from firing... He checked plugs, points, battery etc... All the usual suspects...

I understand the immobiliser works off the computer, but I was wondering if there is a safe way to disable it? AAARRRGGGHHHHH!

Any advice appreciated.

Alex!!!1
Click to expand...

There are different models of the remote entry and immobilizer around. The most common, in the export models, has a flashing red diode on the steering column?
It's likely not the immobilizer, if the remote opens the doors.
If you have the type with the flashing diode, I may be able to help. I managed to disable and bypass mine. A replacement module was unavailable for my model, the whole unit and harness would have to be replaced. An aftermaket alarm was about a quarter of the cost in my case.

Have you tried recovering the MIL codes for your 95? Key on, key off, three times method?
 
Jess said:
usually cps failure will not stop fuel pressure--it will just turn over with no fire and never start.
Click to expand...

CPS failure can cause the fuel pimp relay not to close. You may get a few second prime when the key is first turned to run, but unless the CPS pulses, the fuel pump relay won't stay closed.
There are different kinds of CPS failure, open or short, both can act a little differently, but the results are the same, no start.

2vj7qxi.png


They didn't mention this in the test procedure, but a short (low resistance) between "A" and "B" can also cause a no spark. With the connector connected to the crank position sensor, the violet wire (with the key in run) should have close to 5 volts. If you get a short between "A" and "B" the reference voltage is halved +\-. This can also affect the supply voltage to the sync sensor (distributor) and can cause no engine (MIL) light in the dash.
 
Last edited:
alex673 said:
Hi Guys,

I have a RHD 95 cherokee classic and live in Australia. It's been a good jeep until last night when it decided not to fire up. I had a mobile mechanic come out and he said the immobiliser has stopped the distributor from firing... He checked plugs, points, battery etc... All the usual suspects...

I understand the immobiliser works off the computer, but I was wondering if there is a safe way to disable it? AAARRRGGGHHHHH!

Any advice appreciated.

Alex!!!1
Click to expand...

I would mention to him that this doesn't have points.
 
Jess said:
usually cps failure will not stop fuel pressure--it will just turn over with no fire and never start.
Click to expand...

It can cause the fuel pump relay not to work as 8mud was saying, but you misread what I typed. I didn't say anything about having fuel pressure. I said to check to see if the injectors were firing. If you have a no spark situation and the injectors aren't firing either, then it's the CPS, the coil pickup, or the ASD relay..very unlikely, but it could be the ECU also. Those are the only things in common with the fuel injectors and the sparkplugs.
 
hey all. Just an update. turns out the problem was a blown CPS. Anyway, had it fixed around a month ago and all was fine until a couple of days ago... The damn thing went again! Anyone ever heard of this happening, or do you think there may be an underlying problem causing the CPS to fail?

It cost me around $600 to get it fixed the first time around, and if there is no fault showing up on the part, it won't be covered under warranty. I can't really afford to keep replacing this thing every month or so. Any ideas, info, advise etc. appreciated

Cheers

Alex
 
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