My check engine light is on and my Haynes manual talks about a jumper wire in the check engine harness.
The jumper should be across T and E - according to the book.

There is no T and there are several E's ( E1 E2 etc )
This is a 1990 4 runner with a 3.0L V-6 that is 4 wheel drive.

Can Anybody tell me where the jumper wire goes ?

 

Try TE1 and E1. At least that is what it is on my 92 4cyl, they should be about the same.
Brad

 

Here's what the field service manual says are the correct terminals to use for the 3.0L. Look at page 10.

FSM

David

 

David,

I can't get to the FSM - damn firewall at work will not let me
view that web page. I'll look at it tonight at home.

I e-mailed you earlier regarding the OD sensor on the back of the engine. Apparently my Haynes Manual does not cover everything.

Doc Staley

 

Doc,
David confirmed with the FSM what I said TE1 and E1 are the correct pins to jumper.

Most likley it is your O2 sensor.

Brad

 

Thanks Brad and David !
Where can I get a Field Service Manual for this 4 runner ?

 

Sorry Doc, I'm running into firewall issues too. My company blocks us from getting to external e-mails to prevent us from bringing viruses in and that has prevented me from accessing any messages that you might have sent. I'm glad that Brad was quick to update you with the correct info.

The FSM is pretty expensive.....check out e-bay. In the mean time if you can find a way through your work firewall (or access through another computer) here 's an on-line version. FSM for 3.0L

Good luck,
David

 

David,

Thanks for sending the FSM link - I can view it tonight at home.

My e-mail to you was regarding the overdrive problem that we spoke about a weel or two ago. I've located the water manifold
on back of the intake plenum and there appear to be 4 sensors
screwed into the manifold - which one is the temp. sensor for the
over-drive unit ? wire color code ?
My temperature gauge reads almost half way when the engine is warm and does not fluctuate at all when on the interstate.

I drove to Crossville on Saturday to see the grand kids and the over drive acted weird the whole time - above 75 mph it will stay in overdrive but anywhere below 75 it is liable to down shift going down hill and up shift going up-hill - it does not have any rhyme or reason ! The thermostat appears to function properly. I've talked with Toyota of Knoxville and they do not list an over-drive sensor or relay for this 1990 4 runner V-6 engine. With 200.000 miles the down shifting is not good for the engine as the rpm climbs 1500 - 2000 when it happens.

any thoughts or suggestions ? :cry:

 

My temp sensor acted the same way as yours.....it would rise to about half way, but not quite to the point where it normally should be. This was because the line to the temp sensor was blocked. My overdrive acted similar to the way yours is doing. It would shift into O/D and then shift out mysteriously. I found that since the temp sensor is what controls the shifting into O/D, if fresh, hot coolant isn't circulated to the temp sensor, i.e., the line to it gets clogged, the coolant around the sensor only heats up as the engine heats up. Then as the engine fan cools the engine off, the stagnant coolant around the sensor will cool off until something heats it back up ,i.e., load on the engine or sitting still and building up heat. I had to clear that line that runs from the thermostat housing up to the coolant by-pass block (where temp sensor is). Yes, there are several sensors in the coolant by-pass block but I don't know which is the temp sensor. My problem was fixed by clearing that line. Did you get coolant to flow through that line?......be careful, it will be hot and will spray! I doubt that your sensor is bad if you are getting the gauge in the dash to read something......I think your line is blocked.

David

 

How did you flush the line ? I can see the line running from the thermostat housing back to the manifold but how to flush it ?

Are you talking about the actual engine temperature sender ?
It lloks like it screws directly into the intake manifold and not the manifold on back of the engine - but it is close.

I could remove the thermostat and blow compressed air into the tube running back under the intake plenum - but unless the other end is open it might not clear any obstruction in the line.
Willing to try anything though !!!!!

Thanks for the assistance ! This is a 1st rate education

 

I just figured out what you meant - remove the temperature sender and open the thermostat housing.
Blow compressed air into the opening for the temp sender should clear the line back to the thermostat. I'll try it tonight - if I get home in time.

Doc

 

You are on the right path. However, on my 3.0L there is what is called the coolant by-pass block that the sensor (actually several sensors) screw into. There is a metal tube that runs from the thermostat housing through the guts of the motor and terminates right next to the coolant by-pass block. There is a rubber tube that is u-shaped that connects the metal tube with the coolant by-pass block. I would suggest doing the following:

1) take off the u-shaped tube and make sure that it is free of any clogs and not soft and collapsing preventing flow of coolant.

2) make sure that the metal tube from the thermostat housing up to where it terminates is not clogged. You can take off the thermostat and blow compressed air from the top side and blow anything out the other end (opposite the way that the coolant flows). I would think that anything clogging it will be closer to the thermostat end.

3) If the first two check out and do not show any signs of a blockage, then make sure that the nipple on the coolant by-pass block (where the u-shaped hose connects) is not stopped up).

I hope this is more clear. It is a little off the original topic but I know how frustrating the shifting out of O/D problem can be. I wanted to get rid of my Runner I was so sick of it. I'm glad I didn't because I have got another 70-80K miles out it since I solved/fixed the problem.

David

 

Well Doc, how'd it turn out?

 

It was pouring the rain when I got home and I really didn't feel well. I was sick all day yesterday with the stomach virus that is going around. I did not realize that your body could loose so much liquid and still function ! Both ends - if you know what I mean.

I've bought a new thermostat from Toyota 195 degree's and plan to blow out any obstructions when I change it.
Waiting to feel better at the moment. Me first truck second !

The FSM link that you sent me does not open. It say's the site is unavailable. I'll keep you posted on the progress
Thanks for the help.

 

I just noticed that site went non-functional yesterday. Apparently somebody didn't like us having access to it. When I get my e-mail up and running again, I'll try and send you a pic of the diagnostic plug. Personally, I think that when you clear the clogged line, you won't need to pull any codes because that will fix the problem. Let me know how it works out.