Troubleshoot an intermittant blinking OD Light on 1990 4runner

Periodically, my 1990 4runner will display the classic blinking OD light
with regard to the automatic transmission. When I pulled the codes a while
ago, they pointed towards problems with either the #1 or #2 solenoids or the
wiring to them. I don't recall the exact codes.
Fortunately, the problem disappeared for quite some time. Unfortunately, it
has come back. The problem though is that it may appear while driving and
then disappear by the time I get home where I can install the jumper in
order to read the codes.
As many here may already know, when the problem presents itself, the
transmission goes into limp mode and you have to actually shift through the
range of gears to drive the vehicle. Not a good situation if you need to
pull out in traffic. You have to use plenty of caution.
The strange thing is that when the transmission works, it seems to be fine.
Then when it doesn't, one would think that the transmission is shot. The
fluid is filled to the proper level, is clean, and doesn't smell burnt. It
almost seems like the problem may have something to do with temperature.
Another thought is that there may be a problem with the speed sensor(s). I'm
not sure how many, if any, or where they are located though. I read that
some models have one on the back of the instrument cluster, but when I had
to replace the speedometer cable this past Winter there wasn't one there.
Does anyone here have any pointers on how to go about troubleshooting the
Thanks in advance to those who post a reply to the group.
Reply to
Peter Bogiatzidis
Sorry I don't have a solution, but the codes can still be pulled even if the light turns off again. Any time a problem occurs, the codes get stored on a computer chip. Insert the jumper to read them again. (If you disconnect the battery, the codes get wiped.)
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Reply to
You are correct. I just read that in a troubleshooting flowchart that I found.
I'll have to read the codes again and step through the chart to see if it's either a mechanical or electrical fault.
Thanks for your reply.
Reply to
Peter Bogiatzidis

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