Hi everyone! I'm a long time lurker. I apologize for the length of the post, but I don't like to post questions unless I've done the research (searched posts, etc) and given as much information as possible. I own a 2002 Tundra with the 5VZ-FE 3.4 engine. It's an Access cab, 2wd with automatic. I've had it since it was new and have about 115k on the clock.

About 10 days ago, I got my first CEL. It happened after driving from Phoenix, AZ to Sedona, AZ (approx 110 miles, mostly uphill). I just got off the freeway.

I drove it a few hours later with no CEL or any other issues. I drove back to Phoenix with no issues. I pulled the code P0120 using my laptop. Using PDF version of the FSM, I figured that it must be the TPS itself. I replaced it with a NAPA/Echlin part. CEL was off. I cleared the ECM. All seemed well for a few days. It came back with a vengeance a few days later.

I decided to go back to the FSM and follow it to the letter. I tested the both the old and new TPS per the FSM using a multimeter. They checked out fine. I also checked the circuits out using a multimeter per the FSM and they did not check out.

I decided to go a step further and disconnect the harness to the ECM and the TPS and check for continuity. 1 of 3 did not check out OK. It's entirely possible that I didn't check the circuits out properly, but I think I did it right. I trust my abilities.

With the P0120, the FSM states that it's the TPS, wiring, or ECM. I don't know what the heck happened to the harness, but I'm out of ideas and I'm ready to take the section out to see if its really the culprit.

Even if I get the harness out, where the heck can I get another one? Are they only available used? I may be able to replace the TPS pigtail, but I have no idea where to get that except for the stealership. Before I go that far, I'd really appreciate any advice. I really need to get this beast fixed.

Thanks a million in advance!

 

u can check ur local auto wrecking yard, i would see if any parts of the wiring is been heated and broken.. also by the sound of it, it could be a bad ecu?

 

I don't see any obvious damage to whatever wiring is visible, but there is a lot of wiring I can't see.

I haven't ruled that out yet. The lack of continuity on the VC circuit between the wiring harness ends makes me think a short somewhere. I checked the continuity ahead of the connectors on both ends.

Thanks for the suggestions!

 

why not run a wire from computer to the wire at the tps thats not getting continuity threw it and drive it for a day and see if u get the code again, if not then u know its that wire.

 

I thought about that and am willing to bet that the code goes away. Any suggestions on how to tap into the connectors to try it? Any special tools for this purpose in the aftermarket? I'm used to working on older Detroit Iron, where wiring is not as tight and "easier" to bypass. I'll look into it.

I'm also going to unbolt the conduit and see if any wires chafed against the opening in the firewall.

I'll report back with results this week as time permits. Thanks for your help.

 

I just got back from the garage. I unbolted the conduit from the firewall and looked at the harness. The wire I'm concerned about looked fine. No cuts/abrasions that I could see.

I also bypassed the wire and it made no difference. The CEL stayed/came back on, even after clearing it.

I'm out of ideas for now. Maybe I do have a bad ECU. The only other thing I noticed was the connector looked a little bent on the pigtail. I'll mull it over and see what else I can come up with. I'm open to suggestion.

Thanks again!

 

Yikes, I think I figured it out. I decided to swap sensors one more time. When I took the new one out, the bottom pin was bent like an accordion! I must have been getting intermittent contact after replacement.

CEL is off, for now, but I think the original TPS is failing intermittently.
I'll grab a new one from Toyota and hope it's gone for good.