Rev Counter related to Auto Box fault

[SteveG]

I have a gearbox fault on my 1995 2.5dreported in a very recent topic. I have just replaced the crank/pulse sensor to get the rev counter from behaving badly (intermittently) to no effect as the rev counter is still intermittent which means that the data being sent to the gearbox solenoids is sometimes false.
Tested the wires coming from the sensor (all good) and have made a visual inspection around the back of the rev counter...looks as ok as a floppy circuit can!
Any further ideas as to why my rev counter behaves so badly would be welcome. Do I need a new instrument panel???

[willow2u]

How does the gearbox see this rpm signal

[g8dhe]

The sensor feeds the ECU which then feeds on the signal to rev counter and signals the gearbox once combined with other signals from the road speed etc.

[willow2u]

So the Rev counter probably doesn’t factor into this problem so long as sensor is working properly if the ecu receives the info then sends the pulse on to rev counter

[SteveG]

I was just about to ask if anybody knew the signal order. Makes complete sense now....so I don't need to worry so much about the counter dial.....I have a new sensor......so I probably need a solenoid pack for the gearbox......thanks Bongo friends!

[willow2u]

Also maybe worth checking if the speedo mod wiring (if yours has it)has been wired up correctly maybe someone has cut into something dodgy

[SteveG]

I found a black block wired (3 wires) into the back of the circuit board......wondered what it was! All seemed good. Any way of testing?

[willow2u]

Disconnect it and see if Rev counter behaves differently

[g8dhe]

The speedo chips are 4-wires +12v, 0v, signal in and signal out. Any pictures of where its wired to ?

[SteveG]

Guessing it is a speedo fix(?) as the wire replaced (blue/white) is on the terminal block/socket which plugs in behind the speedo, whilst another of the wires goes to the SP+ on the circuit...(SP = speedo?).
Why does the Bongo need a speedo fix?

[g8dhe]

To convert from KmH to MpH without changing the scale also it causes the odometer to read in Miles rather than Km.