Mark I Computer Diagnostics

From: EMS8110@ritvax.isc.rit.edu
Date: Thu, 18 May 1995 17:52:14 -0400 (EDT)
Subject: Computer Diagnostics

This is directed to Peter and Dan, but I thought it might benefit everybody.
This expains how to read what your computer stored as a trouble code in 1st
generation MR2:

1. Find the service connector (a little vlack box, about 1" square near air
flow meter). Open it. Short terminals marked T and E1 with a wire.

2. Turn all accesories, especially A/C off.
Put the ignition key in ON position. Stare at the "CHECK Engine" light
(amber light on the dash). Count the number of times it blinks in 5 seconds.

3. The codes are:

Number of Blinks:	Code:

	1		Normal
	2 		Air Flow Meter
	3 		Ignition
	4		Water Temp Sensor
	5		Oxygen Sensor
	6		RPM
	7		Throttle Position Sensor
	8		Intake Air Temp Sensor
	10		Starter
	11		Switch signal (A/C switch ON)

Now, the above code are not a gospel truth. Often the computer will deside
something is wrong when it is not, ar will point to the wrong sensor. But it's
a start.
The code will run the light will blink) continiously with 2.5 second intervals
between the series of pulses, i.e. 5 blinks, 2.5 seconds of nothing, 5 blinks,
2.5 secs.... for Oxy sensor. To stop teh insanity, remove the jumper between T
and E1. I highly recommend the following. Do the check, record the problems,
remove the AM2 fuse for 30 seconds (that will cancel the codes in memory).
Drive aound for a week. Check again. That way any old code will be cancel and
the second reading might point to the actual problem. BTW, if ECU thinks there
are multiple problems, it'll give you more than one code, just keep counting
:-)

Please don't hasitate to email me with any questions.

Mike.S

PS. Dan, I gave you some wrong info. The above is from the workshop manual.
Disregard my previous email.
PPS. To all the people who suddenly find that they need )2 sensors. DO NOT buy
one from Toyota. Any single wire sensor will do. They can be had for way under
$50, while Toyota wants $95).