How often do the PSOM units in cluster fail ?
Do the interior lights work? the PSOM has 2 power sources. Start with a check of fuses.
At almost a quarter century on the clock, I'd be surprised if it DIDN'T have an issue! While not common, (mainly because they weren't used in a very wide range of vehicles) they do fail. As another said, check the powers and ground before that. Getting a good salvage or ‘reman’ unit will be tons of fun!
They do fail, and when you need it fixed, get a good cluster rebuilder to do the job. This is not a very expensive repair for that vehicle. Check powers and grounds, and if they all prove out, then get the cluster rebuilt.
As mentioned they have two power sources. That is where you need to start as well as the instrument panel ground wires they are plainly identifiable. And my experience in that era with the instrument panel cluster they have a very high rate of failure, if memory serves me correctly. hth
I forgot to ask was it having transmission issues as in a hard shift or are you referring to the instrument panel itself fluctuation inoperative odometer reading various other failure points that I can remember on these units . A little more information would be very helpful for those that are trying to assist you. ( ? ) INFO NEEDED 🚙 + 🔩 + 🔧 + 🔨 + 🙏 = 🏁🏁 😎
Sorry , I was half asleep . I asked the car gods for help in my sleep . Ask and you shall receive !!! So it has very intermittent ( once a month ) harsh shift with speedo drop . Also has a code for glow plugs occasionally ( 2 times a year ) . my family member purchased this truck a year ago and I looked it over and pulled cluster , replaced diff speed sensor , removed diff cover to inspect tone…
Can you clarify the term overlay from PCM. A twice a year intermittent issue would be very hard to accurately diagnose. Has the problem recurred after you removed and reinstalled the instrument cluster? Possible solder joint in the instrument cluster panel board. I have actually repaired a few with similar issues in the past and it will cause your exact issues that you described. That is why I…
My experience is that when the speedo drops, it's a bad vss or wiring issue to the PSOM. I would see alot of wire breakage in insulation right where harness goes from the VSS in the diff to the frame from flexing. On the super dooper rare occurrences I've caught a PSOM itself causing a P0500, my speedo never dropped out, but it stops sending the vss pulse out to PCM.
What makes me think that it’s psom or after is because the way this one is wired the abs is in parallel with vss before psom . I would expect abs warning light .
Hmmm… this has the abs data link connector under the hood, right? Did you verify that no code is indeed setting in abs module? By all means, I'm not saying it couldn't be a PSOM, I've fixed many an intermittent P0500 with cluster repair/used replacement, but it's just not the most common fix I've personally come across.