|
|
NW Kansas | Help, my good old 93 fld120 has been giving be some problems lately with the tach and speedometer. The tach is sluggish, sometimes reading right, sometimes 500 rpm slow, but not rapping up with the engine like it should. The speedometer reads correct and then after the next corner 7-8 mph slow. I have cleaned and adjusted the sensors on the flywheel and transmission. Seemed to help the speedometer. Then replaced the sensor on the flywheel that goes to the tach and it did not help at all, maybe worse. Local mechanic says put new tachometer in and i'm ready to order one. It just seems odd that both are acting up, and usually if one is right then the other is wrong, like the speedometer is right, then the tach is off, and if the tach happens to be working then the speedometer is off. The sensors make their own pulses and there is no juice going to them, but the have two wires. Could I have a ground problem? Or do i just order the tach? |
|
| |
|
Mount Vernon, WA | You need to get a wiring diagram for the truck and see if the gauges are driven directly by the sensors, or driven by the data bus. Since it has a flywheel sensor, I am inclined to think it has directly driven gauges by the sensors.
If I was working on it, I have a tool that simulates a sensor signal that could help me determine where the problem lies. You could also use a voltmeter and check for an AC voltage and frequency signal at the gauge as well.
If the engine is electronic, the gauges could be driven by the data bus, but I doubt it on a truck that old. |
|
| |
|
East Central SD | I would start by cleaning all the grounds.
|
|
| |
|
Central Iowa | Had the same problem on my FLD112 (1995). Put on a new tach and problem was solved. Hang on to your hat when you pay for it. Wanted mine fixed as other people sometimes drive my truck. |
|
| |
freightliner tach and speedometer
