jaredmac11

edit: FIXED!!!
I studied the wiring diagram completely and traced the purple wire from the ECU to behind the cluster, it appears the wire MAY have bent and snapped thanks to brittle plastic... I dont know how else it'd snap.
After I soldered the wire, I put it all back togehter, turned the key, and the CEL went away immediately.

I gotta say, I LOVE the ES' manual.

1997 Lexus ES300


Continued from old thread: https://www.clublexus.com/forums/es-...e-is-cold.html
Im just starting a new thread since I've investigated quite a bit more from where I was and just want to ask pointed, specific questions. Not trying to clutter the forum, but its hard to pick up in that old thread.

I am having an issue with the P0500 CEL that just wont go away. I bought an OBD2 scanner with bluetooth (PRODIAG Car Bluetooth OBDII Scan Tool awesome device, wholly recommend it) and did some more wire testing.


Diagnostic Observations:

• OBD2 scanner detects my car is at 0mph... even when when the speedometer indicates otherwise and I am in drive, cruising.. I will consistently trigger the P0500 code as long as I am moving and it starts at the first shift.
• I checked the wiring, and I found the following:
  • SPD pin at ECU gets continuity
  • SPD pin at E7 connector gets 10 volts
  • 3-wire speed sensor (with the gear that generates the frequency to the ECU) gets continuity and voltage on each wire (excluding ground).
  • 2-wire speed sensor gets continuity but no voltage.

OK, now for my questions:

1. Do these readings above check out? I assume everything is good there, but Ive read some diagnostics (not from my manual) that continuity at the SPD pin at the ECU means a short.'
2. Does the OBD2 Scanner read the ECU? Can I then assume the ECU is not reading the Speed sensor?
3. Which speed sensor drives the speedometer and which drives the signal to the ECU? I assume each speed sensor performs a separate task?
4. Should the 2-wire speed sensor get voltage at the plug on the harness with the key ON but the car not moving?
5. Can I just swap the ECU? The keys dont have a chip inside them and there is an aftermarket Viper security system in the car.

I'm thinking about selling my car because I just cant get this figured out and can't get it inspected.

Sincerely, I appreciate the input of anyone who is knowledgeable on this issue or wiring harness issues.