Gear Position Indicator-Trouble Shooting

[Thumper]

If your gear position indicator is not working, or not working for all gears/neutral, you can test the sender, and test the Speedo unit and wiring pretty easily to trace the problem.

The sender unit is typically mounted to the engine just in front of the front sprocket at the end of the shifting drum which moves the gear dogs or dog clutches on the countershaft and driveshaft inside the transmission ( ).

The sender has contacts in a concentric pattern that are grounded individually when the transmission is in a gear position. Here is an example sender unit:



The bus connector has these wire leads accessible for testing. All you have to do is see which lead is grounded when it is in each gear with an ohmmeter. I grounded the other lead on the ohmeter and using the red probe for testing here. In my experience, only one wire gets grounded when it is in a given gear position You may have a slightly different pattern, there may be an offset neutral contact, but the way it works should be the same:



For the 5 speed Templar with ZS172FMM-3A engine in my original Templar X, this is what I got:



If some of the gears didn't ground a lead wire in the bus, maybe the contacts need cleaning so it gets a better ground when bolted onto the engine. But if this test went well, you got a good ground in each gear (and one also grounded in Neutral), then you can now test the other side of the bus connector and ground each lead to test your wiring and speedo/gear position indicator. You will ground each one separately, turn on the ignition, and see if the gear position indicator is showing the right gear (or neutral).

I used a short wire with alligator clips on each end and connected a short wire with a female connector to conect to the narrow male spade connectors in the bus that goes to the speedo unit:



Just turn on the ignition when you have one of the leads grounded:



Obviously, your testing on the sender side tells you which wire grounding should light up a specific gear indication. If this part of the test fails, then it is your wiring harness to the speedo, or the speedo itself that is not right. You can do the same testing up behind the light to see if the grounding "signal" is reaching the speedo connector through your wiring harness, and you can ground each one going into the speedo to see if that is the problem. This may not be as eaasy since the bus to the speedo may include not only the leads from the gear position sender, but also power for the unit and other connections. The color of the wires coming up from the sender will guide you to the right wires to test.

If you get a wiring harness and everything is OK except that the gear position indicator wiring in the bus that connect to the sender is jumbled, you can repin the bus to the correct pattern based on your testing.