Please help decode this CEL Blinks to read codes (Video)

[Bulldozer]

Okay so yesterday the ex starts running rough, no power, sucking fuel like crazy. I manage to read the codes and I get what you see in this video.






To me it looks like 118 123 and 11.

118 is Coolant temp sensor voltage too high. The sensor is almost new. I tested the resistance on the sensor at different temps, it's in spec. I check for continuity for both wires to the PCM, they're good. Checked for 5V on the gry/red wire, it's in spec.

123 is TPS voltage too high. Checked for sweeping voltage at varying throttle positions, looks good. Checked for continuity on the wires to PCM and for proper voltage. All looks great!

What else could it be? Either I'm interpreting the codes wrong or bad PCM?

I cleaned all the connectors etc. and cleared the codes. 123 hasn't come back (yet?) but 118 is persistent. After clearing the codes the CEL will come back on within about 15-30 sec. of running.

Thanks in advance for your help!

 

[R1dd1cK]

Well it looks like you counted right to me.

 

[Bulldozer]

Well it looks like you counted right to me.

Thanks for the input! I sure thought I did but its hard to tell and I'm a little thrown off because I'm not seeing a "separator" flash between current codes and stored codes.

Of course I can't find my old coolant temp sensor to try, even though I'm 99% sure I threw it I'm the spare parts box when I replaced it.

I did find my extra pcm that'll ill plug in today and see what happens. Its for an auto trans but I imagine it should work for my diagnostic purposes.

 

[MrShorty]

In addition to not seeing the separator pulse, you also did not get any repeats. My gut feel is that your jumper wire came loose (or something else) and terminated the test early. That final 11 was probably the beginning of the 118 repeating.

Remember that codes point to problems in circuits, of which the sensor is only part. Don't neglect the possibility that there is a fault in the wiring to those sensors. It might be interesting to look at a wiring diagram and see how much those two sensors share in common. I know they will both use the same 5V Vref, and, from their position, they might share part of the wiring harness.

 

[Bulldozer]

In addition to not seeing the separator pulse, you also did not get any repeats. My gut feel is that your jumper wire came loose (or something else) and terminated the test early. That final 11 was probably the beginning of the 118 repeating.

Remember that codes point to problems in circuits, of which the sensor is only part. Don't neglect the possibility that there is a fault in the wiring to those sensors. It might be interesting to look at a wiring diagram and see how much those two sensors share in common. I know they will both use the same 5V Vref, and, from their position, they might share part of the wiring harness.

I did the test like 10 times using a good new piece of 14AWG wire for the jumper and got the same thing everytime. :-/

They do share the gry/red vref but I checked it for resistance from the TPS, ECT sensor, EEC test connector and at the PCM plug and their was good continuity and low resistance everywhere. I also checked the other wires from the TPS and ECT to their respective places on the PCM and for shorts to eachother and they all check out A-OK. I'm thinking my junkyard PCM kicked the bucket.

I am getting about 5.4v on the vRef wire which I know is supposed to be around 5.0, could this be a problem?

Thanks for your input MrShorty!

Edit: Just put my old auto PCM in and let it run for a few minutes. No 118 or 123 code. 2 codes for missing trans solenoids obviously but it actually blinked correctly with seperator flash and all. Does this make it definitive that my PCM is garbage?

 

[R1dd1cK]

Well that does sound like a bad PCM if one does it and the other does not.

 

[Bulldozer]

Well that does sound like a bad PCM if one does it and the other does not.

Which sucks because it's a California emissions manual trans PCM and they are pretty hard to find and junkyards around here charge like $100 for them.

I popped the cover off it and the capacitors all look good. If I can figure out how to get the bottom cover off I'm going to check for broken solder and such and hopefully fix this thing.

 

[Bulldozer]

Just a quick update for anyone that runs into this problem in the future. It has been going strong for a few days now with the other PCM and no CEL.