Quote:
Originally Posted by Rick76
OK.
Your car is a Federal or Canadian version. You have a speed sensor on the rear of the engine that has brown and white wires going to a 2 pin connector C155. It is located to the left of the brake booster (right if looking from front). You can unplug it and check the sensor coil resistance. Also check to ground for infinite resistance.
From C155, wires go to C154 on the back of the cluster. Wire colours are now brown/white (pin 1) and white (pin 2). Pin 3 is the power feed to the tach that comes from fuse 12 (8 amp) and is black/red.
If your sensor checks OK and you have 12 volt power and ground to the tach, then your tach may be at fault. Ground for the tach is connected internally in the cluster and should be checked. Among the things that can fail in the tach is a calibration pot that can open and dried out electrolytic capacitors.
When pulling the cluster remove the plastic clip holding the speedo cable (engine compartment) to allow the cable enough slack.
|
Very interesting. Do you have a diagram showing this kind of setup (tach sensor direct to cluster with no tach amp in between, with connectors C155 / C154? Do you have a car with such a setup? What year, market and VIN?
You said "Your car is a Federal or Canadian version" Is the Canadian version same as the Federal version but different than the California version?
I have an 85 300D Federal version and it is nothing like what you described. I do have an OVP, my bell housing tach pickup goes to the EGR controller before going to the cluster.