L2900 temperature gauge inop

[peanuts]

My temperature gauge stopped working; stays pegged low. I checked the wiring visually, replaced the sender and the gauge. Still inop. Ideas?

 

[North Idaho Wolfman]

Meter the gauge one side should be hot with key on, other is sending unit, ground that side and gauge should climb to top, if that works bad wire from gauge to sending unit.

 

[mickeyd]

Welcome to the forum Peanuts.

 

[peanuts]

Thanks for the good advice. I should have done that first and I would not have replaced the gauge. But, I can short the terminals that plug onto the sender, and the gauge responds by climbing normally. I guess I have a bad new sender. Doesn't sound right, but I don't see any other explanation.

 

[Daren Todd]

Does one of the wires going to the sending unit go to a ground?

Could be just a bad/ loose connection at the plug where it ties to the sending unit? Try wiggling the wires at the sending unit first while someone watches the gauge. If the gauge jumps intermittently then it's just a connection in the wiring

 

[peanuts]

Yes, one side of the plug goes to ground and the other to the gauge. When a jumper is used between the plug ends, the gauge is then grounded and responds by climbing to hot. I've made sure the plug terminals connect to the sender terminals by "closing" the plug terminals slightly so it is a snug fit. Still nothing out of the sender. Anybody know what the ohms reading should be when the sender is hot. Logic would say it should approach zero when the water in near boiling.

 

[peanuts]

I noticed that the voltage at the gauge is only 4.3 but the board has 7v printed on it. What is the source of the 7 volts? In the parts lists I don't see a transformer.

 

[peanuts]

Its been a while since I was on the forum so I thought I would report what the issue was with the L2900 temp gauge. The L2900 has two temp sensors, one near the thermostat and the other at the aft end of the head. It turned out that the wire from the front sensor was OK but the wire from the aft sensor was broken. Caused the gauge to barely register. Repaired wire to the aft sensor and now the gauge works fine.