eec trick?? got it started...

[blazey]

so upon checking into computer problems, and my '91 still not wanting to stay running after changing the fuel filter, i was informed of a way to get trouble codes with the key on and engine off. gray wire all alone by the eec box, i took and grounded this with the key on expecting to get the "check engine" light to flash at me with a trouble code or two. what happened was i heard the fuel pump working for about 3 seconds the check engine light went off and stayed off. so i turned the ignition over and to my suprise the engine touched right off and seems to be running great now. i get a check engine light about once a minute or two but engine starts fine and runs smooth. did i restart the computer? did the computer need to lean out or make the mixture more rich after fuel filter change and the only way to reset this is by grounding ecc gray wire. anybody have an idea of what happened and whether or not i will have ongoing fuel problems now. thanks.

 

[mrboyle]

Is the grey wire still grounded? Either way there is something wrong somewhere and needs to be addressed before it snowballs and starts taking out more expensive parts (ie: ecm)

 

[MrShorty]

Looked at the wiring diagram in the repair guide at www.autozone.com. I see several "gray" wires coming out of the ECM. The most interesting connects the ECM and the ignition control module, that controls the spark plugs.
Like mrboyle said, you need to find out what that gray wire does, why grounding it fixed the problem, and then fix it properly. To that end, get a good wiring diagram. I usually go to the library and look it up in the Motor/Mitchell manuals that our library has. Then, go from there.

 

[Opera House]

Look on

www.batauto.com and on the right side of the screen you can click on tech to get the method to read codes.

 

[blazey]

gray wire

the specific wire is the one that is on the same loom as the eec, it is all by itself, it is used when u are extracting codes with a key on engine off test, counting the flashes of the check engine light. i grounded it, noticed that the fuel pump ran maybe 2 to 3 seconds, when i went to the drivers seat, check engine light was off and never came back on, and the vehicle started. now if it sits an hour or two i have to do the process all over again to get it to fire.

 

[MrShorty]

If you don't ground it, does the fuel pump come on? When it won't start, do you have fuel pressure at the fuel rail?

 

[blazey]

fuel

if i don't ground it the fuel pump comes on for a bit when i turn the key to the on position. i haven't check for pressure at rail when it won't start yet. next on the list. i really am convinced that it is now a computer problem. help

 

[Runnin'OnEmpty]

Blazey, do you have a small ground wire coming off the battery negative cable? If so, remove the end from the radiator support and clean the connection, then retighten it.

Seems like I read or heard somewhere that this wire completed the ground circuit for the ECM. This might not fix it, but it sounds like you have a bad ECM/EEC ground somewhere......

 

[Guy Groves]

I will presume that the 91 and 92 wire codes are the same. They should be.

What do you mean a "gray" wire all alone by the EEC box? There are several gray/"some color" wire from the EEC unit:

pin  3     VSS Dif +  gray/black
pin 26     ACT        gray
pin 29     HEGO       gray/lt. blue
pin 31     CANP       gray/yellow
pin 46     SIG RTN    gray/red  (signal return for all sensors, also used to get error codes from test connector)
pin 47     TP         gray/white
pin 56     PIP        gray/orange

The SOLID gray wire connects EEC pin 25 (ACT) with the Air Charge Temp. Sendor on the upper intake manifold. If this is the wire you grounded then there is probably more trouble than you realize, and it should not have resulted in the fuel pump start-up.

I will focus on one particular circut # 679, gray/black connected to EEC pin #3.
This is the Variable Speed Sensor positive (VSS DIFF +) circut. From EEC pin 3 it T's through a 4 pin connector near the EEC module and connects to the speed sensor module on the Transfer case, and cruise control module under the dash. On my X the wire connecting to the cruise control module is cut (severed completely and it looks like it was cut with wire cutters on purpose).

I'm wondering if your wire was also cut, and this is the wire you are refering to? Mine was cut about an inch after it enters tha cabin through the firewall wire harness gasket. You should be able to locate both ends of the cut wire, you may have to undo some of the wire wrap?

If you grounded the wire on the EEC side then you just grounded out the VSS+ circut, and are probably bypassing the speed sensor altogether.

Is the Speed Sensor bad or disconnected. Have you done anything around the T/C. Check the speed sensor connector at the T/C. Is it connected?

Also check the body ground connection just near the EEC unit. It should have 3 wires: 2 pink/Orange and one black. The pink/orange wires are for the return side of the speed sensor, and the EEC pin 6 VSS DIF - .
The black wire is for the EEC case ground, pin 20. It is VERY IMPORTANT that this ground connection be made properly. The other important EEC ground are the two black/white wires from EEC pins 40 and 60 which MUST go to Battery ground (the negative battery terminal) Just before the get to the battery the go through a 2 pin connector and change to solid black wires connected to the battery negative terminal (These should be OK, or your car shouldn't start at all).

Guy

 

[Guy Groves]

I will presume that the 91 and 92 wire codes are the same. They should be.

What do you mean a "gray" wire all alone by the EEC box? There are several gray/"some color" wire from the EEC unit:

pin  3     VSS Dif +  gray/black
pin 26     ACT        gray
pin 29     HEGO       gray/lt. blue
pin 31     CANP       gray/yellow
pin 46     SIG RTN    gray/red  (signal return for all sensors, also used to get error codes from test connector)
pin 47     TP         gray/white
pin 56     PIP        gray/orange

The SOLID gray wire connects EEC pin 25 (ACT) with the Air Charge Temp. Sendor on the upper intake manifold. If this is the wire you grounded then there is probably more trouble than you realize, and it should not have resulted in the fuel pump start-up.

I will focus on one particular circut # 679, gray/black connected to EEC pin #3.
This is the Variable Speed Sensor positive (VSS DIFF +) circut. From EEC pin 3 it T's through a 4 pin connector near the EEC module and connects to the speed sensor module on the Transfer case, and cruise control module under the dash. On my X the wire connecting to the cruise control module is cut (severed completely and it looks like it was cut with wire cutters on purpose).

I'm wondering if your wire was also cut, and this is the wire you are refering to? Mine was cut about an inch after it enters tha cabin through the firewall wire harness gasket. You should be able to locate both ends of the cut wire, you may have to undo some of the wire wrap?

If you grounded the wire on the EEC side then you just grounded out the VSS+ circut, and are probably bypassing the speed sensor altogether.

Is the Speed Sensor bad or disconnected. Have you done anything around the T/C. Check the speed sensor connector at the T/C. Is it connected?

Also check the body ground connection just near the EEC unit. It should have 3 wires: 2 pink/Orange and one black. The pink/orange wires are for the return side of the speed sensor, and the EEC pin 6 VSS DIF - .
The black wire is for the EEC case ground, pin 20. It is VERY IMPORTANT that this ground connection be made properly. The other important EEC ground are the two black/white wires from EEC pins 40 and 60 which MUST go to Battery ground (the negative battery terminal) Just before the get to the battery the go through a 2 pin connector and change to solid black wires connected to the battery negative terminal (These should be OK, or your car shouldn't start at all).

Guy