Mechanics

93 4X4 - NEW O2 SENSOR, CHECK ENGINE STILL ON

1993 Toyota Pickup

Computer problem
1993 Toyota Pickup 4 cyl Four Wheel Drive Manual 209000 miles

I have a 93 4x4 with a 22re and manual tranny. The previous owner rebuilt the engine recently (< 5000k). The check engine light was burned out when I bought it. I fixed that, discovered a code 21 (oxygen sensor) and 25 (lean condition). I discovered the wires to the sensor were a little mangled, so I cut a harness from a junkyard and spliced it in, soldered the joints to make sure they were good. Replaced the oxygen sensor with a bosch unit. The code 25 went away but the code 21 is still there! What should I do next?

the truck also idles high, (1100-1200 rpm when warm) even though the throttle stop is set as low as it can go and the air screw is screwed almost all the way in. I have checked for vacuum leaks, it has all new vacuum hoses.

thanks
Avatar
Thaddeus
January 18, 2009.




I've been trying to follow the FSM for troubleshooting this problem, and measuring across terminals E1-Vf1 gives me no voltage no matter what. The FSM says to replace the ECM if the oxygen sensor has been replaced and still shows no voltage. Is there a way to test the ECM, or does anyone have advice for other problems to look for?
AD

Tiny
Thaddeus
Jan 18, 2009.
Hi thaddeus,

Thank you for the donation.

I have here the schematic of the diagram for an understanding of situation.


http://www.2carpros.com/forum/automotive_pictures/192750_Code21_93Pickup_1.jpg




http://www.2carpros.com/forum/automotive_pictures/192750_O2Feedback93Pickup_1.jpg




http://www.2carpros.com/forum/automotive_pictures/192750_O2Feedback93Pickup02_2.jpg




http://www.2carpros.com/forum/automotive_pictures/192750_O2Feedback93Pickup03_1.jpg



http://www.2carpros.com/forum/automotive_pictures/192750_O2Feedback93Pickup03b_1.jpg



http://www.2carpros.com/forum/automotive_pictures/192750_O2Feedback93Pickup03c_1.jpg


KHLow2008
Jan 19, 2009.
Yes, that's the same page from the FSM that I was looking at. So. Am I correct? If performing this test reads zero voltage, the ECM is at fault?

Tiny
Thaddeus
Jan 26, 2009.
Hi,

You are getting zero voltage from all test carried out?

If it is recommended to substitute the ECM when the test results are negative, then possiblilty the ECM is faulty.

KHLow2008
Jan 29, 2009.
I have a substitute ecm to try, but I'm wondering what the possibility is of damaging another ecm if there is some other problem that caused it.

I did do the voltage test, all zero.

Tiny
Thaddeus
Feb 1, 2009.
If all the testing shows no shorting of sensors or wiring circuits, then there should be no possibility of damaging the ECM.

KHLow2008
Feb 1, 2009.
Yep, it was the ECM. I'm guessing that damage to the wires caused a short and burned out the circuit in the ECM. Used one fixed the problem.

Tiny
Thaddeus
Feb 2, 2009.

AD