V6 cranking but not starting - run out of ideas!

[Albatros]

Hi all,

This is my first post but I have been using this site for years. I have a 2001 v6 bongo with LPG conversion. its a JAL import & camper conversion.

We broke down on the M3 suddenly and without warning. No warning lights on the dash. Car cranks fine but won't start. I have been troubleshooting ever since but I have now hit a wall!

Working backwards I checked the spark plugs - no spark, then the distributor cap and rotor arm - no signs of excessive wear, then tested the coil - no spark there either. Using a mulitmeter I could see there was 12v going to the coil, but there was no signal leaving the coil down the other wire (I used this chaps very helpful video https://www.youtube.com/watch?v=XyYH49QGtoU). So next I located and removed the crankshaft position sensor and tested it with a multimeter (as per the same chaps other very helpful video https://www.youtube.com/watch?v=RvuzZJqQDf4) and confirmed it has resistance (1010 ohms) and also successfully generates its own voltage.

I figured the next step was to check earth continuity to the sensor, so I backprobed the 2 wires leading to the sensor (one at a time - I did not know which was earth) and created a local earthing point. But still it won't start.

That is where I am at. I am not sure where cable to the sensor comes from - is it the ECU? IF it is the ECU, where can I find it and how to I identify the sensor feed?

Any ideas would be very much appreciated - I'm meant to be going on holiday on Saturday

Thanks all

[Albatros]

I forgot a bit which might be important. I hooked up an LED to the OBD1 and got a P1521 fault code which, according to the handy Engine Diagnostics factsheet from this site (available from the members area), is a VRIS Solenoid '1' Circuit fault. However after reading this post (viewtopic.php?t=55204) I decided it probably didn't matter.

I'd be grateful to hear any suggestions. And if anyone can recommend a garage in Thanet, Kent that would be great too, thanks.

[g8dhe]

You appear to have created two posts for this problem, I'll flag it for attention!

[Ian]

Blimey! I'm not sure I know how to merge posts. So here's a link to the other one, which I've now locked.

viewtopic.php?f=3&t=77491

[Albatros]

Blimey! I'm not sure I know how to merge posts. So here's a link to the other one, which I've now locked.

viewtopic.php?f=3&t=77491

Apologies - no idea how I managed to create the post twice. So is this thread the one that is remaining active?

[Bob]

Yep, this one's live.

Don't worry, it's very easy to double post by mistake (I happen to know ).

Sometimes it sort of double clicks and you don't notice, then you've only got a short while to delete it.

Hope you find the problem soon/cheaply.

[willow2u]

my 2 pence worth is the igniter box near the coil

[nth]

I figured the next step was to check earth continuity to the sensor, so I backprobed the 2 wires leading to the sensor (one at a time - I did not know which was earth) and created a local earthing point. But still it won't start.

I Have never worked on this engine but what do you mean by sensor earth? On an inductive sensor both sensor wires normally go straight back to the ECU, There should be no connection between any of the wires & earth? (both the ECU & sensor should be disconnected to test this.

[nth]

I'll have a look at a wiring diagram later to look at this specific system. In the meantime have you checked for an injector pulse signal? If you have an injector pulse this should confirm that the ECU is seeing the crank sensor signal. If you don't have a noid light to check this you can use an LED test lamp, One side of the injector plug should be live when the engine is cranking & the other should be a pulsing earth.

[Albatros]

I figured the next step was to check earth continuity to the sensor, so I backprobed the 2 wires leading to the sensor (one at a time - I did not know which was earth) and created a local earthing point. But still it won't start.

I Have never worked on this engine but what do you mean by sensor earth? On an inductive sensor both sensor wires normally go straight back to the ECU, There should be no connection between any of the wires & earth? (both the ECU & sensor should be disconnected to test this.

I should have said I checked the continuity of the wires. I had assumed one was ground and was checking for continuity on that assumption. Either way, there is no continuity. Having examined the wiring diagrams closely (with much help from a far more savvy friend) I have since carried out more continuity tests on the sensor's circuit and there seems to be a break somewhere between the crank sensor and the X-35 connector.

These are all very helpful suggestions, thank you all!

[nth]

Is there a component key anywhere for the diagrams? You can work most of them out by the symbols & number of wires but there are still a few that can be confusing.
Also on the components & multi 'X' connectors is there any way to know the pin numbers they connect to? For example the 2 wires for the crank sensor what pins do they go through at the X-35 connector?

[g8dhe]

Yes go to the start and then scroll right, the entire manual is in there.

The X-nn connectors are all at the rear of the manual before the index.

[willow2u]

It’s not something daft like an alarm immobiliser cut into the crank sensor wiring thought I already posted this

[Albatros]

Is there a component key anywhere for the diagrams? You can work most of them out by the symbols & number of wires but there are still a few that can be confusing.
Also on the components & multi 'X' connectors is there any way to know the pin numbers they connect to? For example the 2 wires for the crank sensor what pins do they go through at the X-35 connector?

Yes, I did this yesterday. Fortunately the solid blue and solid green wires from the PCM to the sensor are easy to spot despite the PCM wiring diagram on my Bongo differing a bit from the manual (the plug the sensor is on appears to be the same as in the manual but there are a couple of additional plugs connecting to the PCM) which isn't surprising considering the manual is for older models than my 2001 model.

I think the break is between the X-35 connector and the sensor, at least that is what the multimeter says. I'm going to try a new temporary connection there and see if I get resistance across the wires (while disconnected from the PCM). If I do I'll see what happens when I turn the key...

Thanks again everyone for your input.

[Bongolia]

Silly question maybe but is the rotor arm turning when you crank the motor?