# 1995 Speedometer/Odometer not Working



## iglola12 (Aug 10, 2017)

1995 XE 4cyl. RWD 5speed manual. Speedometer/odometer not working at all. I replaced the speed sensor 6 months ago and it worked great for about a week. I crawled under the truck and found that an animal had chewed one of the wires going to the plug that goes into the speed sensor. Spliced this together and the speedometer is still not working. I found a thread that said there is no speedometer cable for this year. If this is the case, can it be the plugs and wiring? Where does the wiring for the speedometer enter the cab? Any advice on how to trouble shoot this would be greatly appreciated. Thanks for your time.


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## smj999smj (Jan 1, 2006)

Your HB uses a vehicle speed sensor with a pinion drive and a plastic gear, which is driven off of a gear on a shaft inside the trans. It is basically an AC voltage generator and produces approximately 1-volt per 10 MPH. While this is best measured using an oscilloscope to make sure the signal is not broken, an AC volt meter on a multimeter can be used in a pinch. If you pull the cluster, you will see the printed circuit and there are four bolts that hold the speedometer head to the back of the cluster. These bolts create the circuit between the head unit and the printed circuit. Two of these bolts are inputs from the VSS. If you located those bolts, you can attach the leads of your AC voltmeter there to check and see if the VSS signal is making it from the sensor, through the harness to the back of the head. You will need to support the drive wheels off of the ground and run the vehicle in drive, of course. If there is no signal to the back of the head, you can unplug the harness connector from the VSS and run leads to the pins of the VSS and check for output signal. If there is no signal, you have a bad VSS, a stripped plastic gear on the VSS, or, less likely, and issue with the gear inside the trans. If there is a signal, you'll have to find the open or short in the harness between the VSS harness connector and the cluster. 
If you have a signal getting from the VSS to the cluster, then you have a bad speedo head. This is fairly common on mid/late-90's Nissans. The threads in the back of the speedo head (where those four bolts screw into) are known to develop cracks, causing the bolts to loosen and create a poor electrical circuit between the head unit and printed circuit. Sometimes you can tighten the bolts and get the speedo working for a period of time (could be a day..week...months...who knows?). Also possible, is that there is an internal problem within the head unit. Most of the HB speedo heads are no longer available from Nissan. Used units can have the same problem. Your best bet would be to see if it can be repaired; try Circuit Board Medics or Mr. Whizard.


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## iglola12 (Aug 10, 2017)

Thank you for the step by step trouble shooting. I have a friend (electrical engineer) who has an oscilloscope and voltage meter who can help me trace the electrical. When I replaced the VSS, I also replaced the gear that is on the end of the VSS, so that would cancel that potential issue. I will let you know how things turn out. Again, thank you for taking the time to post this information.


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