1995 Explorer XLT - Speedometer Problems

[Steve W4EPI]

First time poster, long time reader...

I started out with my original speedometer working OK but the odometer and trip odometer not working. ("Speedo A") I found a used instrument assembly ("Speedo B") and changed it out. Now, both odometers work in Speedo B but the speed indication itself is not right. It works, but:

1. With the engine running and the car stopped, the indicator shows about 15mph. (Speedo B)
2. In traffic, it reads 15-20 mph high and it responds to speed changes slowly.
3. When the engine is off, the needle rests on the peg below the 0mph mark. That tells me that the little servo meter has free movement.

The only thing I did before installing Speedo B was that I removed the odometer from Speedo A (it read about 144K miles, which is close to right) and installed it in Speedo B. I figure because both the odometer and the trip odometer work, I did it right. I also checked to make sure the plastic needle indicator isn't rubbing against the face of the instrument black panel.

Any ideas of what's wrong? Does anybody know a bench procedure for calibrating the speedometer itself?

Thanks for any and all help.

Steve, W4EPI
Tucker, GA

 

[pugulis]

Just curious, why didn't you just install the second instrument cluster?

 

[Steve W4EPI]

Good question. The reason I didn't just install Speedo B was because the odometer reading on it was way higher than the original. The original shows about 140K, while B shows about 237K.

One lesson learned about disassembling a speedometer assembly is to check the calibration with a AA battery BEFORE you remove the needle, so that you know where to put it back and thereby preserve the calibration. (There is a good movie file on Youtube, explaining how to do it) Now, I am probably going to have to either get this one lab calibrated or buy a refurbished unit. Argh!

 

[Steve W4EPI]

OK, got it fixed. All good now. Here is what was wrong:
1. The needle was pushed "in" too far, and was causing it to bind up ever so slightly. I pulled the center insert off, pulled the needle out a bit, re-installed the center insert, and made sure that the needle returned to zero mph when I moved it
2. Speedometer indication needed calibrating. I did this by using an App on my smartphone and comparing it against the indicated speed. Started out 10mph high, and ended up less than 1mph high. Took about 15 minutes. The key step is to move the needle position while the engine is running, the vehicle is stopped, and the xmission is in Park. This stabilizes the speedometer motor armature position. You can make small changes by pulling the needle off and repositioning it until it's right.

Note that the center insert on top of the needle changes the balance a little bit, so be sure and reinstall it each time you adjust the needle position. Everything works now: speedometer, odometer, and trip odometer.