Well, I have done more checking and I am none the wiser.
I will study the wiring diagrams a bit more before I get someone else to look at it.
The relay is engaging when I connect it up, even though the head light switch isn't turned on but I don't get any lights for the sides or the dipped, etc ...

Thanks very much. I will have another root about.

Thanks. I don't have automatic headlights so not that I am afraid. I have looked at the bulbs and all filaments seem intact. Some more head scratching for me yet.

Got me stumped at the moment.
Last week I returned to the Bongo to find the headlights were on, but I hadn't left them switched on. It had been raining hard and the drain point under the bonnet lip by the windscreen was blocked. I drove home and then took a look under the bonnet. I found one of the ...

Whoop de Whoop!! A very early start to nurse my Bongo to Bath and Bell Hill Garage. By 5pm I'm driving it back home and, trying not to speak too soon, all working properly. The Crankshaft Position Sensor and a faulty VSS wire appear to have been to blame. Tested for about 40 miles by Tom and his ...

A little update. I am now starting to work through parts myself to double check things. I have had the Air Flow meter off to test it but, despite online documents suggesting it's possible, having checked with a couple of auto electricians, it seems it's not. One of the electricians said the symptoms ...

The fault occurs whether driving or idling under garage workshop conditions. I'm not sure if the fans cut in when driving as I can not hear them over the engine. I don't get any warning lights on the dashboard so my gut feeling at present is that it's an issue related the Advance and Retard system ...

I need to double check on the work done so far but I'm pretty sure the Crankshaft position sensor is fine and the rev Counter has been checked to confirm that it doesn't send a fault of any sort to the ECU. It doesn't seem to have a Camshaft one though.

Thanks very much for the diagrams. I can make basic sense out of those but am not sure as to which sensor is which.

I have contacted DCP Tuning to see whether they can re-map the ECU to correct a fault with Advance/Retard, if it has one.

The Lambda, Temp' Sender Unit, Throttle position sensor ...

Right, I have my Bongo back and I'm interested in the Advance/Retard system on it. I'm going to do a little investigation before I look at spending more money or sending it away anywhere else.

Does anyone know how the Advance/Retard works on the V6 Bongo? Is there a specific sensor plugged in ...

A good point, but I don't know if the sensor sends any signal to the ecu. The fan cutting in so often may be because it's idling in the garage workshop rather than out on the open road. It is so long since I have had the car to drive that the symptoms I describe are what I had originally been ...

Thanks for those suggestions. I'll contact them and see what they say. The Bongo came from a dealer in Southampton who sells lots of V6 Bongos so I might give them a try too. If I can find the time I fancy a fiddle myself.

I live in the new forest. The garage I've been using have bongo experience but they probably wouldn't describe themselves as specialists. The fault does limit the distance I van easily travel.

The ecu has been away for testing and came back all clear. They don't test them under load though. Not sure about the distributor retarding but I guess it's built into the ignition system.
Thanks for your thoughts...it's a real foxer!

Got to love cars!!
The Bongo has been in the garage for nearly 6 months and is still exhibiting the same symptoms and the garage is running/has run out of options. The ECU, Fuel ECU, Engine Temperature Sender Unit, Lamda Sensor, Dizzy Cap, HT Leads, Plugs, Rotor Arm, Coil, Intake manifold, Fuel Pump ...