Circa 2000 Mazda B3000 sporadic failing VSS issue
 

Hello All

As per some other threads, I had what I thought was a VSS failure with no speedo, bizzare shifting, disco lights in the cab, etc. This is only when it's cold. The VSS was replaced but as soon as it got cold again the symptoms returned. Our very short summer is upon us in the Edmonton area and the old girl is running beautifully. However I know once the cold weather returns so will the symptoms. I suspect a short somewhere that is triggered by the cold.

So I guess it's a matter of hunting down the short when the symptoms return, however any ideas or tips on tracking this down?
Perhaps a PCM issue or am I on the right track to focus on a possible short?

Thanks

Bill

Welcome to FTE.

Seeing as how this is OBD-2 diagnostics & is fairly sophisticated, maybe consider coming by & learning to use the inexpensive ELM scan tool & running diagnostic freeware FORScan that's tweaked for Ford & Mazda vehicles of your vintage, as discussed here, so you'll be ready when it acts out next time, https://www.ford-trucks.com/forums/1...-scantool.html As this combo can query All of the vehicle computer/controllers, it may be able to focus your trouble shoot. It did for me about 5 years ago on my suddenly appearing ABS trouble code & intermittent acting out power window woes, when it found body controller code clues I didn't know I had because my Actron CP9145 scan tool couldn't access the body controller, or GEM, or ABS controlles, but the ELM / FORScan combo could. It's a really good bang for our diagnostic tool box bucks.
Some thoughts for consideration, let us know how it goes.

First off, thank you for replying Pawpaw.
P0500 has always been the code which is just telling me there is a speed sensor issue. No other codes even with a Autel Scanner Maxisys MS908. That's what lead to the VSS replacement. Everything looked ok after the replacement but as soon as the cold weather kicked in again the problem returned. I'm intrigued with the ELM / FORScan combo. I will have a look at that. Looks like many forums dedicated to that. For $25.00 that's a good deal. I just have to convert it to Canadian Pesos ;-)
What's concerning me is the nature of the cold weather instigation. I so hate tracing electrical issues.

Bill

The ELM can put up live sensor feeds, so can help isolate a circuit trouble shoot, so we don't have to go to every connector in the circuit to disconnect it & make measurements with our multimeter, so can take a lot of work & frustration out of a trouble shoot.

The Autel MS908 should be more than capable of trouble shooting this problem, so being well equipped as you are its not likely you'd need the ELM help on this trouble shoot.

One member had a problem with the wiring harness split case coming loose along the rear axle & whipping in the breeze & causing the wires to break. Another had pinched the speed sensor wire where it runs up over the tranny / engine at the torque converter area & the wire got pinched when the tranny was reinstalled.
Several have reported connector corrosion at the pin / socket interface. So seeing as how this is a intermittent cold sensitive problem, have a close look at the rear differential speed sensor electrical connector to make sure its pins sockets are clean & dry & the connector is sound, no chips, or cracks & its wiring insulation is sound.

Did the problem come about suddenly after some event?

Started last winter without any one distinct event, and I think the diff connector is where I’ll have another look. The truck may be suffering with lot rot as it sat for quite a while during the winter. So corrosion is a good bet.
As for the ForScan, I’m still I going to play with that as I’m an old retired telco guy that knows enough programming to be dangerous. So this open source software intrigues me.