Check engine light on

I went up to the local parts store, but they dont make a code scanner for the older toyota trucks until 1995. I had to do a trip wire and test it. But the problem is, is that the light doesnt always stay on and it doesnt read the code out right.

I checked under the whole bench seat, and there isnt any plug-in things or wires of any sort. The way the manual tells to check the the codes for the check engine light is to make a trip wire and connect T1 to E1 and turn the ignition on, but the light blinks normal when checkin it. Is there a different way to check the o2 sensors and see if they are any good?

Ok, I got out the ohm meter, but where do I find the +B and HT things? I looked at the diagnostics box under the hood and there is a +B but no HT. Is there somewhere else I have to stick the probes?

I tested the o2 sensor. Andi got 3.92, that was at the outside temperature which is aroud 70-75 degrees. So tomarrow im going to go up to discount parts store and check a new one. Hopefully this is the problem. I'll get back to you with what I find out.

I put in a new oxygen senor yesterday, but it aint runnin any better, I turned the truck on and let it warm up, and then I drove it around the neighborhood and almost didnt make it back. I then let it sit in the driveway and the light went off, and it would run for a while but then it would come on and run like crap. I dont know what is goin on with this thing. Hopefully you can help

If the ecm is bad, then whydoes it run soo rough when the light comes on. Oh, by the way, the other day, I started the truck, and I drove it down the road and turned around. On my way back, the truck started stuttering REAL bad. I barly mad it to the driveway. The truck was pretty much jerking everytime it stuttered. When I put it in nuetral to open the gates, my truck stalled. This has never happened before. Would this result be from the ecm being bad? Or could it be the mass air flow?

Help! Was there ever a solution/fix to this?
I have replaced:
Fuel Pump
Fuel filters x2
Oxygen Sensor
MAF Sensor
TPS
Plugs and wires.
Now I sent in my ECU because we can't pull a code even when the engine light is on. The OBD1 does NOT read anything (used several different OBD1 devices). I also tried to trigger the code by using metal contact pin in the Diagnostics box (to watch the engine light flash)

Please help. This is my 1992 Toyota Winibego v6, I am currently stranded in North Utah, My home is in Seattle.

Took it to a shop they said had to be the ECU since it wasn't allowing the OBD1 to pull a code. The ECU was sent in and tested and they couldn't find ANY issues with it.

Still think its a oxygen sensor?
Temperature sensor?
TPS isn't adjusted accurately?
Wire Harness?

I was having the same issue as described above.
I found a temporary fix that lasted awhile-until the past week, If I disconnected the + battery and removed the EFI fuse after each use, put them back before I decided to drive (both immediately). Then it would work like nothing is wrong.
Now I can't get the Engine light off 99/100 times.

Thanks for any immediate help, expertise or thoughts!

Hi Ken,

Thanks for your prompt response. That was one of the last options I thought for the issue.

Have you seen this often cause an issue with pulling the diagnostic code?
Perhaps furthermore not allowing a computer reading.

Could it be the ECT sensor wire? The gauge has been showing normal temperatures. Perhaps part of the wire defected.

I am looking to see if I can find a schematic to where this sensor wire goes and how easy it is to replace.

Changed the ECT (Engine Coolant Temperature Sensor), sent the computer in for testing/repair (no issues found).
Still having the same issue. Any other ideas?
Since I am stranded. I took it into a Toyota dealer today. They said possibly electrical issue but not sure. I hope to hear back soon as I would like to get back on the road. Three weeks in Utah so far and only three days of actual fun.