Bypassing Smart Key 1998 XJ 4.0l AW-4

My 1/98 XJ Sport was recently swamped with fresh water. I dried it out and drove it for another 3,000km with nothing unusual happening.

I didn't use it for a month after I got back, until a week ago when I drove about 100km. Tried to restart and it initially would turn over, but not start. Voltmeter & Fuel gauge were not working. Replaced CKP and still no start & volts & fuel not working. Scangauge II would still not communicate with ECU.

Tried another ECU and gauges all work, and codes P1694, 0700, 1686 & 0000 are present. Not too worried about gearbox codes for now, but would like to know if there is a simple bypass for the smart key module as the nearest dealer is 50km from here. Even a permanent bypass would be an idea as this is essentially a trail only rig.

BTW, I am in Australia, so the laws are probably a bit different.

Sounds like the new ECU you tried has Sentry Key enabled... AFAIK you cannot disable that without first unlocking it using the key. I suggest finding a different ECU to try.

All Australian post 97 cars are fitted with Smart Key, as is the wrecked car I removed the second ECU from. From what you have said, do I assume that one SK module can't talk too another ECU? Can someone suggest a source of non SK ECUs, at a friendly price.

What would happen if I moved the SKIM module from the wreck to the trail rig?

hmmmm... my bet is that it would work, but you would need to have your remotes reprogrammed to send the right code to work with the new ECU and/or SK module. I'm not altogether familiar with the SK system, it is pretty rare over here.

My bet is that you could find a source in the states for an ECU without Sentry Key and it will work fine. But I'm not sure how export vs non export vehicle wiring harnesses differ and you may have to do some modifications to your wiring harness for RHD vs LHD and emissions changes.

Just got back from exchanging SKIM modules. Fired up straight away with the matching key held beside it while using the original key in the ignition. The original keyless entry remote appears to still work the locks.

Will just tape the key to the module and refit inside the column for now and hope someone can provide a non SKIM computer. Current one has 535AD on the side. Does someone have one they want to sell?

Awesome, learn more every day! I need to research SK a lot more, clearly.

EDIT: According to my parts catalog, 535AD full part number is 5604 1535AD for ER0 engine (4.0) DG0 trans (all auto trans, AW4 in this case) and Euro emissions. Can't find any difference in the wiring harness for Euro vs US emissions, just the ECU...

BLU-125 said:

Just got back from exchanging SKIM modules. Fired up straight away with the matching key held beside it while using the original key in the ignition. The original keyless entry remote appears to still work the locks.

Will just tape the key to the module and refit inside the column for now and hope someone can provide a non SKIM computer. Current one has 535AD on the side. Does someone have one they want to sell?

Click to expand...

heya Blu ...

Interesting you got an early 98 with the transponder key system.

According to the info Ive dredged up looking at dealing with the late 1997 setup .... and its problems.

The U.S. has an optional Vehicle Theft Security system ..... and exports got the UN / OZ legislated immobiliser system ...

In both cases the systems are disarmed/not in service on leaving the factory .... and require dealer programming at point of sale.

Both systems when fitted ... automatically activate after 20 engine starts anyway so a PCM/ECU without the system may not be available ... but I'll be interested if you can lay your hands on one - as I will probably do the same.

Carves, my grey one has a 1/98 US build tag on the door, but is OZ complianced 1/99.....& doesn't have body colour flares, so I don't really know what model it really is.

It is, however, back on the road......so my TJ can have a rest.