2002 Montero Sport 3.5L XLS

Out of the blue, the speedometer and odometer quit, all other gauges work fine. Have yet to dig into this one. Code P0500 only one on reader. Still driving with the plug wires flipped on coil 3/6 while trying to diagnose the P0306 (no code recurrence yet, hoping would change to P0303 to confirm bad coil pack).

Found this one link which seems to point to failure of the sensor itself. Mitsubishi Montero Sport

If the speed sensor is not working, will the engine still set codes like the P306?

Speed sensor part number appears to be MR518300.

 

I'm thinking I have an electrical connection issue

Replaced the 3/6 coil as part of P0306 diagnosis, obviously jiggled some wires. Went for a drive speedometer back working fine. Two miles later hit a pot hole, speedo dies then Service Engine Light comes on.

Code reader says:
P0507 idle air control system rpm higher than expected

P0500 vehicle speed sensor A

Drive at least 10-15 miles and no code for misfire.

Awakening this beast after 2 years of being dead with spun rod bearings is becoming a PIA. Mechanical things easy. Queer electrons not so.

 

Little gremlins under the hood
Sounds like some connection is loose or could be a wire with worn out insulation making a quick short to ground connection when you hit a pothole

 

Yeah. I guess I will go thru every connection under the hood that I disturbed. Many of the connectors no longer "snap" when put back together as evidenced by the zip-ties I had to use to hold them together (prior hack garage broke a lot of things....). Will try CRC contact cleaner first, assemble, and then back probe for continuity unless someone has any better suggestions.

Di-electric grease on reassemble?

 

I think a spray on contact cleaner is a good idea. I've used dielectric grease on the light bulb contacts and hate it. It stays on forever and you get hands all greasy and messy every time you handle the connector. I guess I'm just not a fan of it.

 

Well got lucky and found the damaged wires!

There is a vacuum line off the vacuum pot on the throttle body which goes to a device (not sure what it is, cruise control maybe?) mounted adjacent the passenger inner fender well. There is an electrical connector with 4-wires on this device which is fed from the large harness on the firewall.

The wrapped wire assembly was noticeably damaged in 2 locations and the plastic harness wrap looks like it was chewed. Unwrapping the wire assembly, I found 2 of the 4 wires severed and the other 2 with damaged strands and exposed conductors. Stripped and soldered each of them back together, used electric tape on each splice repair, then wrapped the entire assembly and the harness.

Speedometer now back working and no Code P0500. Also, for about a year prior to spun bearings, the cruise control would not work (could turn on and off but it would not set). Now the cruise works.

 

Sweet. Just another reminder that having a P0xxx code does not equal having a bad sensor. I can't even imagine how many perfectly good sensors get replaced simply because someone pulled a code off the CEL.
Good job tracking this one down.
Have you driven it enough to set a misfire code on #3? Do you think it's possible that the wire was not fully seated on the coil before?

 

Still chasing the P0306 unfortunately....

 

Well this repair was short lived. Drove about 40 miles yesterday speedo working fine.

Intense rain storm last night vehicle parked outside. Start it up this morning and drive away no speedo and no check engine light. Drive for about 30 minutes no stored codes but a pending P0500. Park for about 1.5 hours then drive for about 45 minutes still no stored codes. Restart engine after 15 minutes and service engine soon light comes on and now P0500 is stored.

Mind you all thru this still have a slight miss at idle (chasing a P0306 which did not reset today).

Argh...