jjrbus

Does a 93 Toyota pickup with 3VZE V6, automatic have a limp mode in the ECM/computer. Have to ask, I am getting 2 answers on this.
Thanks Jim

millball

Limp mode for what situation exactly??

For sure there is a limp mode for failure of the knock sensor to communicate.

There may be several other 'limp modes' that pertain to certain tranny sensor failures and coolant temp sensor failures as well.

Generally speaking, any time the engine is running in open loop regime, its a 'limp mode'.

Charchee

I didn't know about the knock sensor limp mode but makes sense to have one. I am familiar with the open loop scenario. A lot of people call it limp mode which suggests that it is running in a derated fashion like what happens when someone ignores a check engine warning in a modern semi truck and the horsepower is drastically reduced in order to make the driver stop somewhere safely and make repairs. The open loop mode in our trucks is how the engine would run without input form specific sensors which dynamically modify certain parameters such as timing. It may "limp" but it's not an actual limp mode.

4runner_toy

what are the symptoms?? I had an issue that threw my truck into "limp mode". Turns out it was the ground wire on top of the intake manifold to the fire wall.

MudHippy

Well for one thing the CEL would be on. Is it?

Charchee

I have seen that before too. I don't know what all that wire grounds but I have heard of it being the final solution to a bunch of different problems. Most of which occurred after removing the plenum for whatever repair they were making.

4runner_toy

Mine just melt/burned off and I didn't realize it.

jjrbus

I am chasing down a no start, no spark issue following the flo chart in the FSM. I was also able to use a new coil and ignitor for testing and then had to return.

Today I am off to buy a computer safe test light to check the pulse from the ECM as the final step.

I was told that it was unlikely that the ECM was the problem as there is a limp mode and then told the early Toyota's did not have a limp mode. Who to believe?

Check engine light. I took the dash apart yesterday, the CEL bulb is good, but does not light. I tried grounding the purple wire at the ECM but it still does not light?

Thanks for the responses greatly appreciated. Jim

4runner_toy

Where can i pick up a factory service Manuel?

jjrbus

http://www.ether3al.com/93fsm-mobile/

This is what I have for 93

scope103

Then you have a wiring problem. The Violet (Purple?) wire on ECM (A-5) goes straight to the W pin of the diagnostic connector, then to the ground side of the CEL. You might as well start by checking for 12v at the Black-Orange wire to the CEL with ign-on. Then check for continuity to ground at V (violet) wire, and if no continuity, at the W pin. (both with ign-on, but I don't think it matters).