The diagnostic connector on my 95 4Runner, near the battery, is supposed to be used when you check the timing. Its also supposed to let you see any codes, by flashing the engine light in the instrument cluster.

According to the label under the hood you jumper TE1 and E1 to check the timing. Based on this link OBD Code, I should get any codes from the engine as well.

The problem is, nothing happens when I jumper those terminals. No flashing to indicate current status. The timing doesn't change regardless of the jumper.

The diagnostic connector has paste in the terminals, I assume to keep the terminals from corroding.

Is there something else I need to do?

Cheers,
DrA>

 

You may need to wiggle the wire in the service connector. Sometimes the grease gets in the way. You'll hear the engine idle change when you make the connection.

 

Should there be +12 on one of the terminals to GND?

Cheers,
DrA>

 

does your check engine light come on when you first turn the key to on? mine was burnt out when i got the truck. burnt bulb = no codes even with a computer.

 

I realize this is an old post but was wondering if anyone knows what exactly happens when one jumpers the diagnostic connector, other than timing retards and check engine light flashes?

 

You use the jumper to check if the check engine light is on while engine is running.
To see if there a code plug there jumper in and go set in the seat and turn the key on and watch the check light it should start flashing. To set the timing first start the car/truck after you hook up the timing light them start it up. Look and see where the timing is set at
Them turn off the car/truck then hook up the jumper then start it up and look at the timing it should change. Have a nice day��

 

The jumper only turn the ECU/ECM control off for adjustment try to drive it with the jumper in place and you'll will not be running good at all.

 

Yes it does and it turn after I have it running you should replace the build.

 

NO
How did you find Positive current to the Negative post ?..

 

I realize how it is intended to be used, I'm just wondering what all it actually does when jumpered. I'm probably thinking outside the box again....Obviously it cancels the advance curve in the ECM for base timing but how? Its affecting other sensors and triggering the check light which is in series and parallel to all the sensors and because it recognizes more than one sensor(s) parameter. If I know what sensor(s) is affected by the jumper, I'm thinking those would be the ones to tinker with parameter wise, to fool the ECM into doing something different, be it good or bad. Hoping for a bigger advance curve (knock sensor and ?). My thoughts are based towards the 3.0. which one might as well put a small block Chevy in and get all the power wanted, reliability and the same fuel mileage if not better. My handy dandy service manuals doesn't go there and my hopes were that someone out there may have pursued this possibility and would share if successful or not there tinkering(s), including other engines as well. I've bypassed the Yota ignition with the HEI Chevy module, big coil, etc. to no avail. And the MSD stuff kind of goes in that same direction. What I need is a boat person or high dollar hot rodder to show interest in a Yota engines, because they are able to get newer big and small ECM engines to run good without all the gizmo's. When you look at the 3.0 stats. its there, just how do you get it?

 

Hello there...
Let's see where to start first. All the sensors best controlled by the ECM are not in series. That is the purpose of the check engine light every different sensors has their own code. And it's good to have it that way. but if they were all hook up in series you would have alot patience to check every sensors. I'm working on a 1989 Toyota 4 x 4 pick up 3.0 right now. It was tow to me to get it running. And I do understand that the 3.0 just doesn't seem to have power. I'm a firm believer that all makes model vehicles that come from the Factory the biggest problem is it's Exhaust restriction. And I do go as far as throwing some headers on anything that run on fuel and put their largest pipe that I could find that would fit with Clarence on the vehicle after so I notice I have plenty of power. You can go stir crazy and drop Chevy in your Toyota it's been done but it takes time money and knowing what your getting into.
Been there done that. Now before I go to the distance I tried to see if what I can do to improve More performance out of the factory vehicle. Where there is a will there is a way. So if I left anything out please do let me know.