1999 RS Smog Issues! Pls Help!

[kamm99rs]

I am having issues trying to get my rs to pass smog. It is not a gross polluter but it is tripping a code p1540. I figured out that it is a vehicle (http://forums.nasioc.com/forums/showthread.php?t=2042308&referrerid=253793#) speed sensor code, and went to the ecu to test a few wires ( I found a troubleshooting manual for that particular code). The manual said to check pin no. 24 on the b135 connector on the harness for voltage, but I did everything and I got 0 voltage and 0 ohms... The smog mechanic told me that my ECU was bad because he tried to clear the codes and it wouldn't clear and it only registered the code when the key was on the ON position..

There was a PROECM Powerchip that was installed when a prior owner had the car (http://forums.nasioc.com/forums/showthread.php?t=2042308&referrerid=253793#). One of the wires was tied into that same No.24 harness that I checked so I removed the entire unit and soldered all of the correct wires back together thinking that that would solve the issue but it didnt.

Maybe when that unit was installed they grounded the vehicle speed (http://forums.nasioc.com/forums/showthread.php?t=2042308&referrerid=253793#) sensor wire that comes from the ecu and fried the ecu? I have no idea, which is why i'm asking you guys.. If you need anymore information to come up with a diagnosis, I'll try to get all the info you need I tried to be as explanatory as possible.

Any suggestions?? I need to get this thing registered!

[kamm99rs]

forgot to mention that the speedometer works perfect, no jumping, the car is not in limp mode, and p1540 was the only code that registered..

[kamm99rs]

for anyone who may have the same problem in the future, the problem was the speedometer. The signal goes from the speed sensors in the trans to the speedometer in the dash cluster, then to the ecu. the speedo in the cluster was not sending the signal to the ecu. Checked the ohms on the wire to see if it was broken from the back of the cluster (#10 and green with yellow stripe) and on the ecu harness (# 24 on center harness also green with yellow stripe) ohms should read around 10 according to subaru. It was okay so the only logical problem was the speedo cluster. Replaced it and had the codes cleared and the cel light hasn't came back on since.

[Dan McGinn]

Bad speedo seems to pop up every now and then on GCs. Different code, same fix for early cars with just a speedo cable. Code is P0500 and if the speedometer is working, its most likely the speedometer itself, swap the gauge cluster and you'll be good to go.