What are the likely causes of the speedometer not working?

[Tyler_Smith_28]

Hello,

I have a 1992 Jeep Comanche and the speedometer does not work. I'm looking for ideas on why it is not working and potential solutions.

Thank you,

Tyler

[The86manche]

Is the speedo gear in the tail housing of the trans or tcase clocked correctly?

[Tyler_Smith_28]

I'm going to look into this and get back to you. That would make a lot of sense. If a previous owner had replaced the transmission, and either forgot to or incorrectly reinstalled the tail housing, I could see why I could have this issue.

 

Thank you!

Tyler

[The86manche]

No problem! I did that in my zj once. Speedo stopped working and I didn't realize I has that gear clocked wrong haha

[gogmorgo]

Mine was dropping out on my ‘91 recently.

Couple things that might help isolate the issue to a certain area. If the odometer works but the speedometer doesn’t, it’s definitely an issue with the gauge.

If your cruise control does work then it’s also likely to be the gauge, because the computer is seeing the speed data. If your cruise control does not work, then it’s very likely to be a sensor or wiring issue. 
In my case I was intermittently losing and regaining connection while hitting bumps, and I would also lose and regain cruise. The speed sensor wiring is in one of the bundles coming up the trans dipstick tube. I noticed one of the connectors there seemed slightly loose, and after unplugging and cleaning the connectors at the dipstick I haven’t had another issue. 

[DesertRat1991]

'91 should still be a cable driven speedometer.

 

Have you got under there and looked around? Is the cable intact? 

 

Could the plastic speedo gear in the xfer case be stripped or broken? 

[The86manche]

2 hours ago, DesertRat1991 said:

'91 should still be a cable driven speedometer.

 

Have you got under there and looked around? Is the cable intact? 

 

Could the plastic speedo gear in the xfer case be stripped or broken? 

91 was the first year of ho in the mj, it was wire driven at that point 

[gogmorgo]

11 hours ago, DesertRat1991 said:

'91 should still be a cable driven speedometer.

 

Have you got under there and looked around? Is the cable intact? 

 

Could the plastic speedo gear in the xfer case be stripped or broken? 

‘91 absolutely does not have a cable driven speedometer. Source: I have two of them sitting outside in both 2.5 and 4.0 flavours.