URD O2 Simulator

It's been a while since I have posted any updates but I finally got around to checking the wiring harness this weekend and also ran a few tests based on some links that PSU Taco85 and 98tacoma27 sent me.

The results of the tests are in:

98tacoma27-I checked the O2 sensor per the instruction link you sent and it tests fine. As a matter of fact, the old sensor tested fine too which didn't surprise me.

So.....I proceeded to test the ECM per the link that PSU taco85 sent. This test was a bit more inconclusive. The link I used had a clear diagram of the ECM for a California spec truck but the "non" California spec diagram was a bit sketchy. I had a hard time determining which terminals to test based on the diagram. So what I determined (and feel free to correct me on this) was to test the 2nd row up from the bottom in the correct plug and the 1st and 2nd ones from the left. My explanation of this may not be clear until you look at the link that was sent.

Anyway, based on what I could determine, I only got voltage on the 2nd terminal from the left and nothing from the 1st terminal from the left. I'm not sure what those results mean.

Did I test the proper terminals?

I also tested the voltage down at the plug for the O2 sensor and also got voltage on only 1 terminal.

Should I expect voltage on 2 terminals or just 1?

The inspection of the harness didn't reveal any worn/broken wires or anything else that looked out of the ordinary.

So....can I conclude that I need a new ECM based on these results? I hate to keep throwing parts at it to solve the problem since a new/used ECM is not cheap.

RECAP:
Did I indeed test the proper terminals?

If so, should I also expect voltage on 2 of the 4 terminals at the plug underneath the truck?

Anyone got a good lead on a reasonably priced ECM for a 1999 Tacoma 3.4, 4x4?

 

Much better diagram! Thanks

Now to clarify which terminals I was checking. I was in plug E6 testing terminals 11 and 10. Keep in mind I had that dodgy diagram that wasn't very clear so I may be waaaay off.

But, you sort of have me confused with your reply. Which wire are you referring to specifically? You mention white/red wire. Can you use the diagram in the link to map which one you're talking about?

Also, can you confirm that I should only be getting voltage from one of the 4 teminals on the plug that connects to the actual sensor?


I think we're getting close to a diagnosis. At least I hope so.

Thanks again for your help!

 

OK. I think I'm following you. Pardon the implied ignorance on my part but I'm going to repeat back what I think you're telling me.

Using my tester set on Voltage, I am to test HT1 (E6-11) with red lead and E8-28 with black lead and I should get 9v or so (engine on, not running and 3v running). Right?

I managed to get voltage from E6-10 testing to ground which are my desired results. Correct? Which would also be the same wire at the sensor location (red/white wire). Correct?

I think I'm following you so far.

 

I'm afraid I just had a mental setback.

When I tested E6-10 I got voltage. I was testing it with one probe in the pin and one to ground.

When I tested E6-11, it was dead. I was testing it with one probe in the pin and one to ground.

Where does testing it to E5-28 come into play?

This is where I thought I was following but maybe I'm not.
Those are the correct ones BUT you need to check HT1 with the red lead and the black lead goes on E8-28. That's in the furthest left plug. IGN ON (not running) should = 9-14V. Running should get below 3V.


I DO get voltage on the plug at the front sensor. I haven't checked the rear one though.

 

Theres your problem!!!! try to reinstall it hahaha!!!!

im just messing with you i thought it was funny

 

Good catch on that typo.

OK...I'm back on track with you now that I know that is a ground in the ECM. So my tests weren't in vain.

I'll test and retest all of this again this afternoon when I get home.

I'll let you know how it goes.

As it stands now though if E6-11 is officially dead, I need to start looking for a new/used ECM.



This poor truck spent a good portion of it's life running several degrees out of time when the piston broke a chunk and caused the T-belt to jump SEVERAL cogs. It's a miracle that it would even start and run. Can't imagine that would cause an ECM to fail but it's had a hard life.

 

Good one Wolfgang! I wish that was the issue. I can tell ya once I get this thing figured out, I might have to consider it!

So I did check it again last night and rechecked it about 6 times, pulled the plug, and plug it back in nice and tight several times too just to be safe.

The test still revealed that E6-10 has 12.5 volts in the "on" position, E6-11 is dead in the "on" position. When I say "dead" it's reading like .02 volts.

E6-10 drops to about 1 volt running and E6-11 still has nothing.

 

That's what I was thinking too. Now if a new ECU doesn't fix it, not sure what direction to take.

I've read where a replacement ECU may need to be reprogrammed. Do you have any insight on that? Not sure that Toyota dealerships in KC would be too motivated to help out in a situation like that unless they are providing the part.

Or is this the part where you mentioned that having the same part number is critical?

 

Gotcha.

The "reprogramming" comments were on some that I saw on Ebay. Might have just been a disclaimer for the seller. Who knows.

All I know is that so far you've provided valuable advice and guidance so far and I plan to follow your advice until I have this issue resolved.

 

Lumberwagon, I hate you are having all these problems with the ECM. I'm sure it's setting back your plans on the mods! LOL Anyway, just wanted to let you know I'm here and pulling for you.

 

Thanks man! I know! How can I think about lift kits with this damn CEL issue? It's killin me. Not to mention my URD gizmo took away from my tire fund already. Got a baby due in a week so finances are going to be tighter than a nuns doohickie!

I've been looking for a used ECU since that's the direction that it's pointing to. They range from 89.00 on ebay for one that looks like it was in a fire to about 300.00 from other salvage yards. Hoping to find one for cheap since it's still an "experiment" at this point. At least I consider it an experiment until the light goes out and stays out.

The part number I need is 89661-04460.

 

LOL! i saw the burnt one on ebay for $89. Good luck buddy! Keep us posted.