Hi guys. Been reading many of your posts and advice regarding a non starting 1990 V6. Mine has been imported from Japan so is Japan spec. That said there don't seem to be too many differences apart from which side the steering wheel is on. I did have a look at the UK Pajero forum but with no disrespect to them they don't seem anywhere near as knowledgeable. So I wondered if you would be kind enough to help?

The car cranks over but will not start. This problem happened suddenly with no indication of anything being wrong before hand. Using your advice I have done the following:

1. Checked for a spark. None at plugs or from the coil.
2. Measured Coil resistance at primary and secondary. Secondary seemed a little high so replaced the coil. No difference.
3. Checked the Power transistor - continuity seemed suspect, so changed that. I tested the new one - when connecting the + side of the 1.5v battery to term 1 the resistance between terms 2 and 3 dropped but not to nothing (same as the old one)anyway the new one made no difference.
4. Checked the voltage on the primary side of the coil (removed the connector and checked the voltage on the wire side) when the key is first turned to "on" it reads approx 5.5 to 6v and increases over say 15 secs to approx 8v where it stays.
5) If I leave the probes in the wire side connector when I crank the engine the voltage drops to almost zero. When I stop cranking after a few seconds I can hear the ECU click and the voltage returns to 8v.
6) Checking the ECU with an analogue meter, I get the continuous sweep pattern indicating the ECU has no logged faults and is OK.
7) Have checked the back of the ignition switch and it is clean with no carbon build up.
8) Recycled the connectors on the sub-fusible link that you guys say can corrode. Then checked the voltage by disconnecting the connector to the loom and grounding first the white wire then the blue/red one and both read 12.2v.
8) Have had a look inside the ECU and can see no signs of damage/burning/corrosion. the two dodgy resistors look fine and do not appear to be leaking.
9) I think I have found a relay in the ignition circuit. It clicks when I turn the key to "start". There are 4 connections at the bottom, a large gauge blue wire and Blue/red wire are connected on one side and a smaller gauge red/blue and black wire on the other half. I'm wondering whether this has simply worn out and will find a new one.

In the meantime I've run out of ideas. The thing thats puzzling me is the low voltage to the primary side of the coil and I feel I should resolve that before going to the distributor and ECU which seem to be the only two things left to check. Any suggestions?

Thanks in advance.

This sounds familiar to what I experienced last year when I got my engine put back together:

3.0 rebuild - look near the end.

For me it came down to it being the ECU and a faulty "new" fuel pump. I was able to pull codes from the ECU and it didn't have the typical leakage but after getting the ECU fixed (for about $150 and lifetime warranty) all was good.

Thanks for thet Pvdub. I've a feeling I need to get the 6v at the coil issue resolved before getting the ECU refurbed. With or without the ECU the voltage at the coil is around 6-8 so the ECU is not causing it. In fact I should have resolved the low voltage before buying a new coil and power resistor but I thought it would be one of those and therefore an easy fix - wrong.... Any ideas on the low voltage at the primary coil?

Welcome! You've done well to check/replace what you have using the search forum, so I don't think anyone will point you in that direction. <img src="/forums/images/graemlins/kewl.gif" alt="" />

My suspect would be the ignition switch rear half - a replaceable electrical portion with a short pigtail harness. They're fairly cheap from the dealer - $25 or so - and the replacement takes only a few minutes. I'd try that next.

There are also a couple of connectors on the passenger side inner fender.... IIRC one is for the coil lead. You could try separating those connectors, cleaning with spray contact cleaner (Radio Shack) and cycle the connection a few times to get a better contact.

Frank

Thanks FrankR. I'll do that tomorrow. Its difficult to see that the problem is anything other than a bad connection on the presumption that there should be 12v across the wire connector to the primary side of the coil. I suppose its more likely resistance is the problem - hence the disappearance of the already low voltage to the coil when the engine is cranked.

With the ignition switch in the RUN position, you should have ~12v at the coil primary even when the engine isn't cranking or running.

Frank

Frank, thanks for confirming. I disconnected the ignition/starter switch wiring connector to test it. Between the ACC connections there was complete continuity - no resistance. In the "On" position which added a connector there was about 20% resistance which fluctuated...

So I'm hoping the switch is indeed the prob and have one on order from Mitsubishi for GBP35- (around $65-). Will update once installed.

It sounds like you found the culprit.

Frank

Unfortunately not. Fitted the new ignition switch today - some resistance too but didn't fluctuate. In the "On" position now have 8 to 9v at the coil, which again disappears when I crank the engine. Can't be the ECU as the voltage at the coil was the same even if I removed it. Fed up. Even called the breakdown company to see if they can identify the prob - useless. Just confirmed no spark.....

Have you checked the power transistor?

Actually, I think it could be the ECU, since the ECU triggers the transistor, which in turn fires the coil. If the power transistor is shorted - or held to ground - it would bleed the coil off.... as resistance.... before the coil could load.

I may be wrong because I haven't seen it happen.... but I suspect it could happen.

Frank