SES light and code P0005

[Mark Rinker]

Vehicle speed sensor fault. Anyone know what sensor this is? 2002 K2500

[DriveAbout]

Vehicle speed sensor fault. Anyone know what sensor this is? 2002 K2500

I had that same problem when my transfer case self destructed in my 2006. It seems as if the metal chips in the transfer case collected on the sensor and caused the fault. It was explained to me that the sensor is used for the speedometer display.

[Mark Rinker]

Since this is a new(er) xfer case, I'll hope its just a faulty sensor, or loose connection.

Thanks for the response, I'll be poking around that area looking for root cause. Meanwhile, I cleared the code and it hasn't yet returned in 80 miles driven today...

[npauli]

I know nothing about this particular sensor, but I've got some experience with a variety of speed pickups from some time spent in engine development a few years ago.

The most common type of speed pickup I've seen is really simple, really reliable, and really cheap. It's just a coil of wire wrapped around a magnet - same technology as 99% of electric guitar pickups. The magnetic field caused by the magnet makes anything nearby with iron in it magnetic too. The coil senses changes in magnetic fields as the nearby iron moves. Usually the pickup is aimed at gear teeth or other teeth that are only used for timing. Some like to see a an endless stream of the same kind of teeth. Others like to see a blip once per revolution. Some even see a stream of teeth with one tooth per rev missing or somehow different from the others.

If you're getting an error related to any speed sensor, I'd guess your problem would be one of the following:

1) The gear or toothed wheel that the pickup sees is damaged. Even a little chip on a tooth might confuse the software that tries to interpret the signal.
2) Metal debris get stuck on the magnet, as DriveAbout mentioned. Just clean off the sensor, put it back, and do whatever you have to do to make sure there isn't more of the same debris around to cause more serious problems.
3) Broken/intermittent connection on the sensor - either in the coil itself or somewhere between the coil and the computer. Measure resistance to find these. I don't know exactly what to expect for automotive pickups, but guitar pickups are (I think) in the neighborhood of 100k-1M ohm. This is probably the only reason to replace a speed sensor.
4) Sensor is too close or too far from what it's looking at, so it gives a signal weaker or stronger than the computer is expecting. This is probably the least likely, but still possible. I'd imagine automotive sensors probably have some idiot-proof installation features so that it's hard to install in the wrong spot.

Hope this helps

[Mark Rinker]

SES came back on yesterday. New codes:

P0540 - Unknown fault
Nd000 - Unknown fault


Aside from some mild/moderate injector smoking at idle, truck is running fine.

What gives?

[Mark Rinker]

Truck came back from a 3500 mile trip with:

P0500 Vehicle Speed Sensor
P0540 Unknown fault
P0700 TCM
P01094 Unknown
nD000 Unknown


So, I am ready to replace the speed sensor. However, I see online 3 such sensors on the vehicle...one for the transfer case, two for the Allison...

Anyone with experience on this matter - specifically the P0500 code? Transfer case or Allison?