Since I got my van, the speedometer has never worked. I replaced the transmission speed sensor, rear ABS, sensor, and checked the wiring to no avail. Computer throws a VSS code, and speedo does not work. Checked the ring inside the output shaft, and it does turn when the output shaft turns.

Now, a new issue has popped up. A week ago, my voltage went up to 16 volts. I pulled all three plugs out of the ECM, since I know it controls the voltage, and plugged them back in. Voltage went back to 14.1 volts under 1500 rpms, then 16 above that. Then I tapped on all three connectors lightly, and voltage went back to normal.

Now, every once in a while under hard acceleration, or at high speed (90+ mph), voltage goes back up to 16 volts. WTF?

Would it be wise just to replace the computer at this point?

 

It sounds to me like your problem could be with the 3 connectors. Either they are dirty or the metal connectors have spread and are not making a good contact.

 

Blasting out both sides of the connectors with crc electrical contact cleaner got me proper alternator function back. No help on the speedometer however. Got to keep searching on that one.

 

The Use if Di electric grease in the connectors at the PCM is a good idea

 

The speedometer itself might be no good. You could try eBay or a junkyard for a replacement to tryout. If that doesn't solve it, you can resell the cluster on eBay and get your money back.

 

Would a bad speedometer generate a vehicle speed sensor error code?

 

Keep in mind that your voltage regulator is built in the PCM. You can send your PCM off for testing and repair to SIA electronics if you suspect it. Google them, they are in Southern IL. My alternator was over charging and I has some other intermittent problems and they all went away after they repaired my PCM. The tech told me on the phone that over time the sodder joints on the PCM break loose that hold components on the board due to vibration. They must be right because I have had no issues with my PCM since they repaired it.

Turn around for me was less than a week but I am in the same state they are located in.

Jason

 

Also for others that send the PCM via mail, insure it and use delivery confirmation via USPS Priority mail.