Wiring Diagram - Urgent Help Needed Options

[6G96GT]

Anyone know where I can get a full wiring diagram for the MAP sensor for a 1996 Celica GT?

[Rusty]

would it be in here? 6gc repair manual from the sticky

[eMrock32]

What is your problem that you need to find the harness? Rodent problems? Throwing a code? I can help you through whatever problem you seem to be having. I have posted a few pictures below of screen shots of my program I use at work. I can get more information if you want, but the 3 pictures combined shows what all hooks into that circuit, and then into the ECU.

[eMrock32]

Here is the Diag ladder to help you try to find a wiring problem, or sensor problem.

[6G96GT]

Thanks for the help guys, I really appreciate it.

My scan tool read the following:


20140222_221153 by SonOfNemesis, on Flickr

And the thing is, after I replaced it, it ran good for a few moments and I thought that was that. Well I tried starting the car yesterday and it started up fine but then died. When I finally got it to run on it's own (without having to give it gas), it ran like crap.

I checked for vac leaks, tested all fuses and even the fuel pump, fuel sending unit, and the EFI as well. Plugs and wires look good. Cap and rotor are good. I do have arching (tested the coil).

After the MAP was replaced, I cleared the memory with my scan tool and the same error screen came back immediately...that threw me off because usually it would take some time before it would do that. Has to be a short right?

Trying to decided what to do next...

This post has been edited by 6G96GT: Feb 23, 2014 - 2:50 PM

[eMrock32]

Same code both times? Does your scanner have freeze frame? How did the connector look? Terminals clear of corrosion or anything? (Look down in it, the very top of the connector isn't good enough if there is corrosion inside of it. And the pins also need to be somewhat spring loaded to push against the pins in the sensor.)

Next idea check for voltage. You need to test the power and ground on the circuit. You cant put the ground wire on the frame or battery. You need to actually see the voltage going to the sensor. If that is good, you need to ohm the signal wire going back to the ecu. I can pull up a ladder test for that code as well.

Voltage is on the outside wires.

This post has been edited by eMrock32: Feb 23, 2014 - 5:09 PM

[6G96GT]

I'll do what you said and report back. Thanks man, seriously thank you!

[eMrock32]

Apparently there isnt a ladder for that code and basically just gives you the information that I have just gave you. The outter wires hsould be giving out 5 volts. If they arent, you need to probe the pins of the ecu and see if they are giving out 5 volts. If computer is, and map connector is not, there is a short somewhere. The tricky part is, that a ground to the positive side of the circuit, could in fact drag the 5 volts down. Ive seen it. That sucks to find. But then, you need to check the middle wire ohms to see if it is connected to the computer with a strong current.

If you have no ohms, then you need to find and repair the break in the wire. Usually just done by replacing the wire since it already broke in one spot, and will continue to break in more.

Your connector could still be bad though as well which is usually the case over wiring problems. When checking for voltage, make sure you dont force the volt meter leads down into the connector. This will leave it with a bad connection until you would have to replace it. Wiggle the leads around though and wiggle the wires will doing it. The key must be on the run position for you to check this. If the current breaks while moving the connector around, or the wires around, you have found your problem depending on what you are moving at that moment.

If you have lower voltage than 5 volts, back probe the wires before they enter the connector. This would also rule out the connector if it has the same, or more voltage there. if its still low voltage before the connector, test the pins on the ECU. If they have low voltage, clip the wires off but still leaving enough to solder, or butt slice the old wires, or new wires back onto it. If you still have low voltage with the wires clipped, you sir have a bad computer. If it jumps back up to volts, you have bad wiring and should replace what you clipped off.

That should test all of the components to go wrong on that circuit. Keep in mind it does have another sensor on that circuit, and if you have to replace the wiring, make sure that one gets new power and ground wires as well or you will get the code for that one. Ill try to help as much as possible without seeing the car so ask freely if you are having a hard time. You could also pm me if you want and Ill give you my number to text since it might be easier.

[6G96GT]

This is really great info, thanks!! I'll do all of this and see what's happening. I'll send you a PM as well.

I wasn't able to clearly see your map sensor diagram. Is it possible you can magnify the map sensor wiring a bit?

[eMrock32]

One more thing, You should be able to unplug it and run the car without it hooked up. The computer should go into limp mode and calculate its fuel off memory and not the readings coming from that sensor. That may help you If you HAVE to drive the car, but I would advise against it. If you have it unplugged and the car still runs like crap, its not that sensor. You still need to repair whatever is broke, but something else is causing it to run funny.


EDIT: If you click on the photos, it takes you to my photobucket which you can click on maginfy on there and see it as big as I had on my screen. I just did it and it makes it bigger. The first 2 diagrams are the same, just the second photo shows it further up the diagram for the reference number running off of the page. The third diagram is a new page that is continues on (comes in from the right hand side), and goes into the ECU.

I can email them to you if you would like.

This post has been edited by eMrock32: Feb 23, 2014 - 5:19 PM