240 Odometer not working, gear is fine

[BassGuy]

1990, 245. Odometer is not working, and I'd like to use it for mileage. I took it apart, and there is no sign of the common broken gear syndrome. I have a speedometer unit from an 86 torn apart right now, too, and they look about in the same condition. It was a known working unit (that I fried with tach power in a no-tach dash ). So I'm wondering where else to look; is it the motor? Do the "centers" of the motors go bad?

 

[vlvman]

The sensor is on the back of the rear diff. Check wiring to the sensor, sometimes the wire breaks close to the sensor from the axle movement.

 

[BassGuy]

That would entail the speedometer not working, right? Mine works.

 

[TrickMick]

1990, 245. Odometer is not working, and I'd like to use it for mileage. I took it apart, and there is no sign of the common broken gear syndrome. I have a speedometer unit from an 86 torn apart right now, too, and they look about in the same condition. It was a known working unit (that I fried with tach power in a no-tach dash ). So I'm wondering where else to look; is it the motor? Do the "centers" of the motors go bad?

go HERE / READ this: http://cleanflametrap.com/speedo.html
pretty "tech" (unless you're an "old timey radio kinda guy....then it's straight up)
may give you insight (and has MEASUREMENTS YOU CAN USE....)

 

[15A]

I've replaced bad motors before. If you have the 86's and know it works, its the same motor. Just swap it out.

 

[BassGuy]

Gonna whip out the soldering iron tomorrow (later today?) and reflow the motor contact points. Looks like a cracked solder joint.

 

[cleanflametrap]

Gonna whip out the soldering iron tomorrow (later today?) and reflow the motor contact points. Looks like a cracked solder joint.

That's what it is. The motors don't "go bad," just the joints crack, and of course if you had replaced the motor, you'd have reflowed the joint.

 

[BassGuy]

Thanks. I found that before, which lead me to inspect the joints. Going to re-flow them tonight.