Electrical question with the speedo

[sotal]

We have a slight bug that we have to work with on the Bongo (I believe it is quite common).

On a fairly regular basis we get no speedo and the HOLD light flashes. It seems to have no ill effect at all, the Bongo changes gears correctly and is completely usable - you just don't get a speedo.

It seems to happen on a second journey, ie. If I start up in the morning, it will work perfectly, but then if I stop off at the shop a few minutes away then start again it will likely produce the fault. I don't think it has ever happened on the first start of the day.

Switching the Bongo off and starting back up again fixes this but it is annoying to do and not always safe. The HOLD light doesn't start flashing for a good few minutes either so often I don't notice until I've got going, then I could be on the motorway etc.

I've been told that it is normally down to the speedo converter.

So first question - is there a known fix for the above issue?

Secondly if not is there a power cable to that area that I could momentarily disrupt with a push button in order to reset the speedo and save restarting?

[g8dhe]

The most common faults seem to be the converter chip mounted normally on the back of the dashboard, they are a very crude circuit and frequently fail normal to by pass them and change the scale. The other common cause is a dodgy sensor at the rear of the gearbox.

[Tony x]

When we removed the convertor chip (which was supposedly one of the better 5 wire versions) the change to how the Bongo drove was dramatic with much better acceleration from low speed.
Worth doing for this reason alone although some get along with them fine apparently.
A switch like you suggest may be problematic as the speedo feeds the ecu and, if the Bongo doesn't know how fast it's going then it won't know which gear to select but you could suck it and see.
One or two of the four or five wires to the converter powers it I seem to remember so there's a place for your switch.

[nth]

I had very similar symptoms, mines had a speedo chip fitted when i got it. I removed to chip & never had another issue with it. I used it as an excuse to fit the ‘plasma’ type dials

[sotal]

So the best bet is...

https://www.ebay.co.uk/itm/173762274337?ul_noapp=true

Black dial with MPH. Remove the old one and put that in the place of the original one.

Then remove the chip from the back ensuring that I reconnect the wire that was cut to put the chip in? (If I have understood the instructions correctly)

Then I'd have a working speedo that hopefully wouldn't have the minor hiccups, but as a negative my trip counter would then count in km and the BOngo would be restricted to 112mph!

I might give that a go.