Speedometer is stuck

BIGPAYNE69

MEMBER
2002 NISSAN FRONTIER
3.3L
V6
4WD
MANUAL
180,000 MILES

I was driving down the interstate the other day and my truck shut off doing 80 MPH. I pulled over and realized the positive ring terminal had broken and come off. I fixed it and got back on the road but now my speedometer is stuck at about 150 MPH and doesn't move while I am driving. I'm not sure if this forum is even still active but has anyone seen this before or have any idea how to fix it?

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

Most likely a real easy fix.

Thank you for including the recent history leading up to this. Your experience gives me more confidence in the solution. This happens to other brands of vehicles too. Older vehicles used a cable-driven speedometer with a spring-loaded pointer. Those always went back to "0" by themselves.

Being a newer vehicle, your gauges are pointers attached to "stepper" motors. A stepper motor doesn't spin like we think of normal motors. Those have an armature that is placed to a specific position by a computer that pulses the motor's internal electromagnetic coils with varying voltages and polarities. As such, the computer puts the speedometer pointer at 0, but it does that gradually as the vehicle slows down. What happened at 80 mph is the power to the computer was suddenly interrupted, so the pointer stayed there. Later, when you restarted the engine, the computer pulsed the speedometer to go back to "0", but the motor does that by rotating the shortest way, which in this case is clockwise.

There's a small peg at "0" for the needle to rest on. At this time the needle is on the back side of that peg. The computer only knows it's asking the motor to rotate to the current speed. It doesn't know the needle is stuck behind that peg.

There's three ways to reset the pointer. The hardest is to disassemble the instrument cluster to the point that you can push the needle counter-clockwise to near "0". That's the last resort when nothing else works.

Next is to find a mechanic with a scanner that can talk to the instrument cluster and do tests on the gauges There will be a process to run the pointers all down to "0".

The easiest way to reset the pointer is to simply drive fast. Look for the speed that is straight across from "0". As an example, if that is 75 mph, once you drive faster than that, the shortest way to that speed from where the pointer is now will be counter-clockwise. That is when the pointer will jump to 75 mph. From there it will resume following the commands of the computer.