87 300D Clock, Tachometer doesn't work

[Mauidieselpetr]

hey, trying to fix above mentioned problem…all other functions on instrument cluster work correctly………for these two:
-CLOCK gets 12 volts from rd/wt wire
-TACHOMETER gets 12 volts from bk/rd/vi wire and signal from gn/yl wire…
I'm thinking….where is the ground ? Is it OK ?

ANY EXPERIENCE WITH THIS ISSUE ?

Thank you for help.

Petr.

[Wodnek]

Originally Posted by Mauidieselpetr

hey, trying to fix above mentioned problem…all other functions on instrument cluster work correctly………for these two:
-CLOCK gets 12 volts from rd/wt wire
-TACHOMETER gets 12 volts from bk/rd/vi wire and signal from gn/yl wire…
I'm thinking….where is the ground ? Is it OK ?

ANY EXPERIENCE WITH THIS ISSUE ?

Thank you for help.

Petr.

If the Tach goes out and the ABS system goes out at the same time, look at your overvolt protection relay. (no idea if this is the case)

[Mauidieselpetr]

Thank you, WODNEK, Overvoltage Protection Relay K1 was the first thing tested…it is working correctly.

[jay_bob]

I had this happen to me recently.

The right pod grounds through a strap on the back of the speedometer pod to the left pod. The left pod grounds via wire #1 of the 15 pin connector.

Chances are you also lost your glow plug light too. Unlike all the other bulbs it only has a hot wire and relies on the right pod housing for ground.

[Mauidieselpetr]

i think that problem is in ground, but glow plug light works correctly….

[Steve_in_NV]

Originally Posted by Mauidieselpetr

Thank you, WODNEK, Overvoltage Protection Relay K1 was the first thing tested…it is working correctly.

No disrespect, how did you test the relay? If the fuse was blown and you replaced it, the relay may still be bad. My tach didn't work and my fuse was blown, replaced fuse still didn't work so I pulled the relay and gave it 12VDC the coil didn't pick up. Bought new one and now tach works. That OVP relay powers up the EGR control unit, however no connection to clock. Do the courtesy lights work? If not maybe fuse. Their may be two separate problems.

[Mauidieselpetr]

here is how i did tested K1, short video:
https://youtu.be/dM32gT7Fs3o

[Mauidieselpetr]

And here is what i have found after taking apart instrument cluster, short video:
https://youtu.be/o1hjvAk7hp0

[jay_bob]

The loose resistor definitely will keep the tach from working.

The clock only ticks once every 20 seconds since it does not have a second hand and is very small. The gold capacitors can fail and that will shut down the oscillator that drives the coils that tick the clock. Search around there is a thread on this failure.