V6 turbo coolant temperature

well done, good work. Unless you already know, the Legend JohnC has made a few detailed "speedo fix" posts in the members area.

Yes, I know I have read all the posts, changed the electric speedo motor, gearbox sensor and checked the wiring. Still nothing. I need to know on what pins does the signal come from the gearbox sensor. I have a repair manual until 87 models and looks like I have different plugs behing the gauges. I have an 89 model. I want to check with an osciloscope if i receive signal from the sensor. If the sensor is ok, the gauges might be the problem

I need to know on what pins does the signal come from the gearbox sensor.

All the connectors are the same which ever model year the speedo is installed in.
Here is a diagram of the pinouts of the large 15 pin connector mounted on the left hand side of the instrument unit.
Take no notice of the info on the bottom of the page which is irrelevant for your purposeses.
As you can see, the speed sensor signal comes in on the second row down from the top.

Speedo pinouts.jpg

Have you done this test making sure you are connecting the 6 volt battery to the correct speedo board connector ...... The SMALLER one of the two .... Red & Black wires ?

IMG_1961.JPG

Yes, the speedo works when i supply 6v. I will check if the sensor sends signal in the plug behing the dash. If the signal is ok, what could not work in the gauges?

We have had trouble before of a member not fitting a speed sensor correctly. The sensor must be inserted fully so that the holding bracket sits on the flange marked on the picture below by the arrow, not where the small screwdriver is pointing.
I suggest the shaft where the "O" ring is positioned is smeared with an All Purpose Grease before inserting.
Could be worth checking.

Speedo clamp.JPG

Have you done this test making sure you are connecting the 6 volt battery to the correct speedo board connector ...... The SMALLER one of the two .... Red & Black wires ?

I can tell that example picture isn't my speedo unit John, it's about 110,000 mile short!

I can tell that example picture isn't my speedo unit John, it's about 110,000 mile short!

........... I am afraid I can't remember who's unit it was.