Greetings all you repair guru’s out there. I have had an issue which I am unable to solve at this time. As stated in the title, I have a 2000 Isuzu rodeo s fwd v6 SUV. While driving on the road recently I lost my speedometer, odometer, and cruise control. The odometer is digital and I can still read the display when the car is on, however the number never changes. There is a little over 185 K on the odometer. I did some research on my own and figured the problem was my vehicle speed sensor (VSS). I thus bought one, changed it without problems, yet my problem persists. Now when I drive for a bit, and come to a stop my vehicle sometimes stalls. Not all the time though. I figure even though the VSS is good (I changed the second one I put in again for a factory VSS and still I get no change) maybe the signal isn’t getting to the ECM. What are my other options for the issue? Could it be the cluster behind the console? Is there a speedometer cable in this vehicle that could be causing this problem? Is there some little selenoid somewhere that is bad and is causing these problems? With the cost of repairs from a garage these days, I would like a couple of informed ideas before I bring it in so as to keep the cost to a minimum. I would like to fix this vehicle in the hopes that it will last another 5-6 months when I will have saved up enough money to buy a newer vehicle. Thanks for all the help and advice any of you give. Love the show and hopefully I can get some helpful advice such as click and clack tend to give.
In looking at the wiring diagram, the VSS signel goes to the speedometer head and through the speedometer head to the odometer/trip odometer electronic unit in the gauge head.
The VSS signel also goes to the PCM which also provides the cruise control commands. It is independent of the speedometer signel processing.
The VSS gets its power from the PCM main relay through a 20 amp fuse. But if the power was not getting to the VSS sensor the PCM would not be getting power and you would have a no start condition. It appears that the VSS grounds the signel line so there must be a pull up current source for the signel line. This could either be in the speedometer circuitry or most likely in the PCM circuitry.
If you can figure out a way to break out the wiring to the VSS, you could measure the supply voltage; check the ground; see if there is an open circuit voltage on the signel line; and scope the pulses from the signel lead of the VSS. Then you will have to track where the signel doesn’t end up.
Hope this helps.
Thank you for your speedy response. I was hoping it wouldn’t be this involved a process, one in which a mechanic could take 20 minutes, or 20 hours given many factors including honesty. Hopefully it’s just a bad ground wire/strap otherwise I fear this could be anywhere from an affordable fix to a “might as well buy a new car, fix”. Any other input from others out there would be welcome and appreciated as well. Thanks again.