Fixed speedometer issue (kind of)

[bobbyk3]

Speedo quit working a couple weeks ago. Put in a new VSS and no help. After weeks of checking wires and continuity I finally found the issue. Power to the TruSpeed speed sensor calibration unit came out of the fuse box. Plugged it back in last night and speedometer worked. Driving down the freeway this morning the speedometer started to bounce a little around 60MPH. Only bounces around 5-7mph, but still bounces around. No check engine light and jeep runs great. What should I be looking for?

 

[Chris]

Speedo quit working a couple weeks ago. Put in a new VSS and no help. After weeks of checking wires and continuity I finally found the issue. Power to the TruSpeed speed sensor calibration unit came out of the fuse box. Plugged it back in last night and speedometer worked. Driving down the freeway this morning the speedometer started to bounce a little around 60MPH. Only bounces around 5-7mph, but still bounces around. No check engine light and jeep runs great. What should I be looking for?

View attachment 123611

A few things I'd check:

Make sure the TruSpeed unit is properly calibrated. Sometimes, if the calibration isn’t set correctly, it can cause the speedometer to behave erratically.

Double-check all the wiring and connections leading to and from the speed sensor and TruSpeed unit. Any loose or corroded connections can lead to inconsistent signals.

Since you already replaced the VSS, ensure it's installed correctly and seated properly. Even a new part can sometimes be faulty, so if you have a spare, it might be worth swapping it out just in case.

Check for a proper ground connection. A weak or intermittent ground can lead to erratic readings.

If you have access to a scanner or diagnostic tool, check the vehicle speed signal to see what it reads while you drive. This can help determine if the issue lies in the speed sensor or the speedometer itself.

Finally, if you've checked everything else, there could be mechanical issues within the speedometer itself. This is less common but something to consider if nothing else works.

Keep us updated on your progress! Good luck, and I hope you get it sorted out soon!

 

[bobbyk3]

A few things I'd check:

Make sure the TruSpeed unit is properly calibrated. Sometimes, if the calibration isn’t set correctly, it can cause the speedometer to behave erratically.

Double-check all the wiring and connections leading to and from the speed sensor and TruSpeed unit. Any loose or corroded connections can lead to inconsistent signals.

Since you already replaced the VSS, ensure it's installed correctly and seated properly. Even a new part can sometimes be faulty, so if you have a spare, it might be worth swapping it out just in case.

Check for a proper ground connection. A weak or intermittent ground can lead to erratic readings.

If you have access to a scanner or diagnostic tool, check the vehicle speed signal to see what it reads while you drive. This can help determine if the issue lies in the speed sensor or the speedometer itself.

Finally, if you've checked everything else, there could be mechanical issues within the speedometer itself. This is less common but something to consider if nothing else works.

Keep us updated on your progress! Good luck, and I hope you get it sorted out soon!

Thanks for the info! The power supply for the calibration unit has a blade attached to the end of the wire that plugs into the fuse box. The instructions say to pull fuse #9, insert the blade on the hot side and put the fuse back in. That's not possible. There is a slot to the right of #9 that is hot, so I put it in there. Maybe the signal is getting noise or it's not a tight fit. I'm thinking about getting a fuse tapper and hooking the units power wire to that and plugging it into the #9 fuse. Something like this (pic). That will be a more secure fit and be in the fuse that the instructions call for.

 

[bobbyk3]

A few things I'd check:

Make sure the TruSpeed unit is properly calibrated. Sometimes, if the calibration isn’t set correctly, it can cause the speedometer to behave erratically.

Double-check all the wiring and connections leading to and from the speed sensor and TruSpeed unit. Any loose or corroded connections can lead to inconsistent signals.

Since you already replaced the VSS, ensure it's installed correctly and seated properly. Even a new part can sometimes be faulty, so if you have a spare, it might be worth swapping it out just in case.

Check for a proper ground connection. A weak or intermittent ground can lead to erratic readings.

If you have access to a scanner or diagnostic tool, check the vehicle speed signal to see what it reads while you drive. This can help determine if the issue lies in the speed sensor or the speedometer itself.

Finally, if you've checked everything else, there could be mechanical issues within the speedometer itself. This is less common but something to consider if nothing else works.

Keep us updated on your progress! Good luck, and I hope you get it sorted out soon!

Thanks for the info! The power supply for the calibration unit has a blade attached to the end of the wire that plugs into the fuse box. The instructions say to pull fuse #9, insert the blade on the hot side and put the fuse back in. That's not possible. There is a slot to the right of #9 that is hot, so I put it in there. Maybe the signal is getting noise or it's not a tight fit. I'm thinking about getting a fuse tapper and hooking the units power wire to that and plugging it into the #9 fuse. Something like this (pic). That will be a more secure fit and be in the fuse that the instructions call for.