Speedo / Converter Lockup

[Buckeyebutch]

2000 TJ 4.0 Auto 152K

Yesterday I started driving the Speedometer started going from actual speed of 35 to all over even down to a six o’clock position during this time the converter went into lockup mode. All this happened for about 20 seconds after that it was fine .
Any ideas?

 

[Jerry Bransford]

Has anyone ever installed a replacement speedometer gear?

 

[Buckeyebutch]

Has anyone ever installed a replacement speedometer gear?

Not that I’m aware of. Bought it in March in Phoenix and drove it back to Ohio been good so far. I did have new u-joints put on the front maybe 100 mi ago

 

[Jerry Bransford]

Not that I’m aware of. Bought it in March in Phoenix and drove it back to Ohio been good so far. I did have new u-joints put on the front maybe 100 mi ago

It does sound like the speedometer gear is not spinning correctly, which is usually caused from having been replaced but not installed/adjusted correctly. The speedometer gear housing has to be rotated to a new position when a different speedometer tooth count is installed, like when different size tires are installed. If the housing isn't rotated far enough, as is common, the plastic speedometer gear will eventually strip out and cause speedo problems which the ECM depends on for proper torque converter operation.

Here's a good webpage that describes the speedometer gear install process... it just doesn't stress enough how important it is to get the speedometer gear housing rotated properly for good speedometer gear engagement. Improper rotation can cause problems exactly like you described.

http://www.4x4xplor.com/speedo.html

 

[Buckeyebutch]

Thanks I’ll look into that

 

[KCsTJ]

My speedometer would do the same thing, the needle would randomly sweep over to the 3 or 6 oclock position then back to normal.
This problem began when i got it back from Eagle Transmission.
They didnt reposition the wires at the transfer case going to the Speedo gear. Wire loom was laying loose and flopping around.
I repositioned the wires around the transfer case in their proper position with zip ties and the wandering speedo needle stopped immediately and the issue has never come back.