Odd electrical behaviour

[Russell Jupp]

Good afternoon,
hoping someone can help out with a weird electrical issue.
Customers' 2.5 td Bongo, in for an intermittent problem.

Ignition on.
No glow plug lamp.
ALL cooling fans running all the time.
Hold button disabled.
It will start eventually, but when driving, it seems to be starting off in 2nd or 3rd gear.

Randomly, it'll do this 4 or 5 times out of 10.

Then, it will be perfectly normal.
Until the next time.....

Anyone shed any light please?
Cheers
Russ

[gilly99]

Bongos are a joy eh! .... to try narrow it down, suggest obtaining the diagnostic codes as per the club factsheets and report back.

[Northern Bongolow]

Check the operation and voltage of the glow plugs, could be low voltage from battery, then check voltage to the rail. Is it damaged or shorting. If all tests well you could remove/replace glow plugs. Starter motor contacts failing is another maybe, they are known to fail inside the starter itself, can be replaced.
The fans coming on is signal from the ECU that something on the starting side is faulty.

[Russell Jupp]

Thanks for that....
I should mention that when its behaving normally, everything functions as expected.
Power to the glow plug relay, and on to the glow plug bar, glow plug light on, etc etc. And it starts instantly.

But when it has a meltdown, no glow plug light, the glow plug relay isn't being activated, the fuel pump cold start doesn't click, and all the fans are running. and HOLD function disabled.
Starter motor is spinning perfectly, battery is good.

Wondering if its an ECU failure.
I don't like electrics, even less when its intermittent.
Russ

[g8dhe]

Have you checked all the earthing points that exist? Some of the symptoms are typical of multiple failed earth connections, a lot of the earth connection points, but not all, have a common connection to them as well as the individual circuits needing earthing, hence its critical to check all earthing points as its likely that more than one has failed!

[Russell Jupp]

The plot thickens.....
Yesterday afternoon, it was doing its usual....

ignition on.
No glow plug light.
All fans running.
Whilst I was stood there scratching my head, without warning two soft clicks from somewhere, and voila...

Fans off.
Glow plug light on.
Everything normal.

This morning its perfect....
WTF is going on?

Forgot to say, I did check and remake all earthing points I could find. It still was playing games.....

Russ

[g8dhe]

It sounds like you have an intermittent somewhere, always the worst thing to track down!
Best way is sit down with the diagrams see here https://www.igmaynard.co.uk/bongo/forum ... 68#p723668
and plan to use a multi-meter to check the supply for each of the main circuits. First X01 fuses, then X02 circuits and finally X03 circuits then wait for the condition to appear and see where the supply is broken then its a case of following the circuit back up to see what is causing the failure.

[Russell Jupp]

Good afternoon,
hoping someone can help out with a weird electrical issue.
Customers' 2.5 td Bongo, in for an intermittent problem.

Ignition on.
No glow plug lamp.
ALL cooling fans running all the time.
Hold button disabled.
It will start eventually, but when driving, it seems to be starting off in 2nd or 3rd gear.

Randomly, it'll do this 4 or 5 times out of 10.

Then, it will be perfectly normal.
Until the next time.....

Anyone shed any light please?
Cheers
Russ

[Russell Jupp]

All sorted!!
Narrowed it down to ECU failure.
Had, another bongo in for mot, swapped ecu and bingo!!
Thanks everyone.
Russ

[Bob]

Well done.