Speedo

[mrdeano]

Is there a switch that affects the speedo please?

[lpgimports]

message is unclear, what are you trying to say or ask? what is the fault?

Paul

[mrdeano]

I want to be able to turn the thing off as I do heaps of miles off road

[scanner]

I want to be able to turn the thing off as I do heaps of miles off road

Is that so that you don't pay "Road User Charge" for km's driven off road?

All you need to do (so I'd guess) is cut into the blue wire on the back of the speedo and insert a switch - but I think it will cut off the signal to the whole thing not just the odometer so no speed or distance reading - not that it matters off road I suppose.

Just looked on Google Maps and I must have driven past your place back in January on my way from Nelson to Punakaiki.

[321Away]

do u mean blue/white trace?
julian

[scanner]

do u mean blue/white trace?
julian

Probably - long time since I looked it, but it maybe blue from the km/mileage conversion chip to the back of the speedo on mine though.

As he's in NZ Mrdeano won't need or have a converter though.

[mrdeano]

Cheers for that,much appreciated

[mrdeano]

Will cutting the wire affect the computer controls in any way?

[mikeonb4c]

I get confused by all this but have I read that the speedo data is part of the data that controls the autobox gear changes?

[scanner]

I get confused by all this but have I read that the speedo data is part of the data that controls the autobox gear changes?

You may well be right - there's only one way for mrdeano to find out.

[mrdeano]

I'm having enough problems with the bongo right now, without any more,only owned it about six weeks and can't bleed it, so staying away from anything else until I am positive I know the result. Just thought I would ask if any one knew. No use paying for road miles when there is no need too when off road.

[mrdeano]

Getting ready to address the speedo problem now, does any one know how the gear box will be affected if I cut though the blue cable? If I do cut through this cable, I wil put a bullet connection in just in case eh!

[patnben]

Getting ready to address the speedo problem now, does any one know how the gear box will be affected if I cut though the blue cable? If I do cut through this cable, I wil put a bullet connection in just in case eh!

If you have an auto gearbox you will definitely need to maintain
this signal to the ECU. If you have a manual gearbox you may get
away with it, the logic says yes but the computer might say NO.

The logic for the auto gearbox is a bit confusing as far as I am
concerned. If you fit a speed converter module it divides the
speed sensor frequency by 1.6 approximately and then passes
the signal on to the speedo head. Doing this doesn't seem to
upset the gearbox in any way, it still seems to change gear at
the same speeds etc. So in this case you would expect the original
gearbox frequency to go directly to the ECU with a parallel
circuit to the speedo head.

It's a known fact that a faulty frequency converter module will
cause error signals from the ECU, so you would expect the speed
sensor circuit to be from the gearbox to the speedo head and
then onto the ECU which conflicts with the parallel logic.

Before you cut the Blue/White cable to the speedo head you need
to know this either by continuity testing or making sense of
the Japanese wiring diagrams. There are others on here with
far more patience than me to resolve the diagram issues and I
for one would appreciate some help in this direction.

As the odometer and speed indication are integrated into the
speedo head, you would lose both facilities unless you would
be prepared to strip the speedo head and do some internal surgery
to get the speed indication working without the odometer.
When the ECU circuit issues have been resolved you could cut
the cables and fit a dashboard switch with confidence.

[patnben]

Further thoughts.

If we look at the problem from a mechanical point of view, the
speed signal to the speedo head is a track on the instrument
panel PCB which terminates with a fixing screw to the speedo head,
simply removing this screw should remove the signal to the speedo
head without interfering with any hidden connections to the ECU.
You now have a simple ON/OFF switch but you need to think how
you might transfer this to an external switch. I wouldn't consider
cutting the PCB tracks because it's very easy to melt the plastic
PCB backing but with a bit of thinking you could probably find
a solution but you do need to replace the fixing screw as it's
part of the speedo head support.

[dave_aber]

Fit a switch in-line in the blue/white core to the speedo unit. You won't affect the auto-box. If modifying this line could affect the auto-box then adding a kph/mph conversion chip would also affect the auto box.

IIRC, the wiring to the odo motor is via a set of pins soldered onto the speedo PCB, which the motor unit plugs into. You could (with a bit of playing) identify which pin to disable to stop the odo counting up, and then wire it out through a switch.

Not sure of the legality of this in NZ, or the reasons why you would want / need to stop counting up the KMs - presumably you have to pay a road use tax based on mileage? Is your mileage checked annually, or are there spot checks?