I have a 1996 Nissan Maxima, about 146,000 miles on it, runs great… And I even understand what the problem is. The problem is, I don’t know how to fix it.
The VSS and all the wiring to the back of the speedometer is fine. This car’s circuit then has a wire, deep inside the wiring harness, that comes back out of the instrument panel and to the ECU. It is in that wire that people commonly get this problem.
I understand why this reading is important for the ECU; it really is important for the ECU to know how fast the car’s going, to calibrate mixture, timing, etc. So when it loses this signal, it activates the ECU.
The most prominent side-effect of this is that it’s intermittent, and when this signal drops out, the cruise control deactivates. If the signal drops out long enough, the CEL comes on and the cruise control light flashes, and deactivates. Usually, within 30 seconds, the signal is restored and the CEL DOES NOT come on. Once in a while, though, the signal is lost for too long, and the CEL comes on.
My question is, how does one fix this wire? Nissan forums say to pull the instrument cluster, tighten a couple screws, clean up some contacts and put it all back together. I did that, and the repair lasted about 6 months before the problem came back this weekend.
Does anyone have a suggestion for a more permanent fix?
bump
I doubt the wire itself is the problem but it could be the termination connections at either end of the wire or the sensor output itself being the problem. If the contacts are clean and making good connection at both ends then the sensor may be the trouble.
If the sensor was bad, I believe the speedometer would either not work or would behave in a random way; it’s not doing that. This connection to the ECU is on the other side of the speedometer, meaning that the connection to the ECU is somehow compromised.
One method I’ve heard to fix them is to replace the instrument console. Legally, those can only be bought new and installed by a dealer, so they can set the mileage on the odometer. That’d be about $1,000. Ouch.
I’m gonna guess that the contacts oxidized after you cleaned them before. You could keep them from oxidizing by cleaning them again, pack the connectors with silicone grease (or, whatever Nissan recommends), and put back together. Connections can often be “wiped” by taking them apart and putting together, several times. Then, pack with silicone grease.
I found this LONG post at a Maxima website:
http://forums.maxima.org/showthread.php?t=321894&highlight=p0500
I think I’ll just try it again. In other words, I’ll take your suggestion. Money-back guarantee?
Added: Never mind. It passed its inspection. I am relieved…
(Here’s my original post:)
Just to get back to this for a moment, I own a scanner, and was able to verify that the problem is as I described (P0500, VSS, if anyone’s keeping score out there). So I used my scanner to clear the code, thinking I was done.
Fast-forward to today, and I took it in to have it smogged, and because I hadn’t driven it enough since I reset the CEL, the car hadn’t gone through all its diagnostics, so it FAILED. Grrr.
I blame myself. I’ve had the renewal notice since December, and the registration is due this Sunday. So I left it until TODAY to have it smogged. I am, indeed, an idiot. But, man, I did not know I needed to take an extended trip in order to have the ECU run all its diagnostics. Oh well. I think I’ll be paying a fine now, for late renewal on my registration.