164 speedo wiring

[bteoh]

My 1991 3.0 V6 12v 164 has a low reading speedo. Most likely related to a faulty sensor in the auto gearbox. From what I have read, it is in a difficult position to access and replace.
I bought a Jaycar speedo corrector and was hoping to see if it will fix the problem.
Does anyone know which wire behind the instrument cluster controls the speedo?
Any help is greatly appreciated

[V AR 164]

My 164 had this exact same problem. I swapped over a working instrument cluster and it worked perfectly. I believe the old speedo was out of calibration because it had been sitting for several years. I doubt your issue would be a faulty sensor, although I could be wrong.

Maybe try getting a working instrument cluster and seeing if it fixes your problem before you start messing with wiring. If you are located in Melbourne you could maybe swing past and I could let you try one of mine to see if it works.

Also I have a workshop manual and wiring diagram, I could send you some pictures although I am unsure if I have a wiring diagram for the speedo.

Andrew.

[bteoh]

Hey Andrew,
Thanks for your input. I did swap the instrument cluster with another and it was the same problem. They could both be faulty but I thought rather than risk buying another second hand unit, it might be a better option with the jaycar unit.
Just need to identify the input speedo wire and it should be ok....question is which colour wire?
Cheers

[colcol]

Allthough they are not the same, i have had heaps of trouble with 33 speedo's, i have generally found that the gearbox sensors either do work or don't, but the ones that don't work have no resistance on the red and white wires, but have some resistance on a working sensor, there is an uninsulated wire on the sensor, don't check for any resistance on it.
The wiring to the speedo and in the speedo assembly, once again, either works or not.
The slow reading speedo's that i have had, had been old and sitting in wrecking yards for years, and are just worn out electrically, but on a 33 Jaegar, speedo there is a pot adjustor, that can be turned clockwise or anti clockwise to make the speedo read faster or slower.
See if the 164 speedo has a pot that can be adjusted.
The jaycar speedo corrector is for different wheels and gearboxes being used that upset the speedo accuracy, and i was going to buy one until i discovered the adjusting pot, Colin.