I got a p0135 code on the pre cat o2 sensor. I reset the computer then I got a p0132 code. This made me figure I had a bad o2 sensor so I replaced it with an NTK. Truck was running great the it stumbled when I checking the tranny fluid. When I got back in the truck I had the p0135 code again on the brand new sensor.

I wondered if the problem is the connector since I had to splice the connector to this harness after an engine fire. I checked continuity from the splice to the pins on the connector and they were all good.

I thought that 2 of the o2 wires will have power to them when the key is in the on position so I checked for it and none of the wires on the pre cat OR the post cat o2 have power to any of the wires when checked with a test light. I checked at the splice and at the pins and got nothing. Do these trucks have to be running for the o2 to get power? (The test light was working properly when I touched it to the battery then I went immediately to the wires and never moved the ground)

Now I'm stumped. Did I get a bad o2 sensor? I know I can drive with the p0135 code but the cel bothers me.

 

O2's are powered thru the ASD relay. That relay will kill power after about three seconds if it doesn't see the engine turning.

 

Ok that makes sense. Why would it throw the p0135 code again? Power should be flowing if there is continuity right?

A bad o2 sensor from the store? Bad ASD relay? What would cause the stubling a bad iac?

What is the full name of the asd relay? I tried to look up asd relay at rockauto but it pulled up every relay on the truck.

 

Automatic Shutdown Relay.

If you engine starts and runs, it is working.

Do you have a scanner? Can you see what voltages are doing with the engine running?

 

Only "scanner" I have is the one that you use with the Torque app on my phone. What Voltages are you talking about the alternator? I have a couple multi-meters I can check the voltage at the battery quite easily.

It starts and runs fine. I drove it to the parts store about 10 miles away. I parked and got out to check the tranny fluid. While checking the fluid the motor started to stumble. I got in and revved it a little bit and it idled fine after that so I shut it off and went in the store. After I got out of the parts store and started the truck it threw the P0135 heater failure code.

Edit: I should add that when I got home and parked it I heard a fairly loud hiss(after shutting it off) like a vacuum leak but by the time I got the hood open it had stopped. Would a large vacuum leak causing the stumbling? Maybe the brake booster?

 

You wanna see what the O2 voltages are doing. Should range from 0 to .1 volts, or is that 1 volt? Something like that. If the voltage is out of range, or doesn't change, or you get no reading at all, you have an issue.

 

What wires are you talking about? The signal wire? The heaters should be 12V right?

 

O2 signal. The value the PCM uses to determine current mixture ratio. Torque should be able to read that. Value needs to bounce around fairly quickly. If it doesn't, sensor, or wiring, are bad.

Edit: Scratch that. Was thinking wrong code..... 135 is heater failure.....

Ok, grab a friend, have him cycle the key on/off while you test wires. Heater is 12 volts, sensor source should be 5 volts.

Dark Green with White trace is power feed for heater circuit. Brown with Violet trace is ground, which is controlled by PCM. With engine running, B/V wire should show continuity to ground. If it doesn't, check the connection at the PCM. (connector 3, cavity 8) If it all checks out good, PCM has failed.

 

OK I checked it with Torque and 1/1 was a flat line. 1/2 was mostly flat but bounced around a little bit.

Looks like I will have to check the connections at the splice. What color wire is signal on the harness? IIRC there is a green, white/grey, 2 black or maybe 1 black and a prupleish color.

While the truck was running it threw p0135 and p0132 again.

Will the truck run if I disconnect the o2 sensor so I can test for 12v on the heater?

 

I think tan/white is the signal wire, black/light blue goes to ground..... The wiring diagram is not exactly informative, and I think there are some misprints...