Ok so I did what i never thought I would do. My question is... Is it garaunteed to fry the ECM if you start your car with the A and B diagnostic terminals crossed. The car ran for about 10 secs before i realized it and turned it off. Thanks in avance. And yes my car is runnning horrible right now.

 

No problem here. You just put the ECM into "Field Service" mode. This is similar to the regular KOEO "throw code" mode, except it can tell you if the engine is in open/closed loop, or if it's running rich/lean.

 

Then how come my car will not run? The battery won't hold a charge or it's not charging. or something cause when i drive the volt meter gradually goes lower and when i give the car gas, It wants to stall out like it's getting flooded cause there is not enough spark to burn the fuel. How do i get out of Feild service mode?

 

Your ECM doesn't control the field charge in the alternator. Your alternator is dead and you are running off of the battery. Which, I would guess, has a voltage of close to or less than 11 VDC. Voltage much lower than this won't generate the kind of spark required to fire your plugs properly. The primary windings in the alternator have to have a certain voltage going through them to produce a strong enough magnetic field to induce the higher voltage in the secondary windings.

To get out of field service mode, remove the jumper from the ALDL.

What you want to do is check your fan fuse in the fuse block. If that is blown, then the alternator won't charge since it doesn't have a reference voltage. Then go to your alternator connections and check for a bad BAT wire, proper voltage at the red and tan/white wires (with the key on but the engine stopped). Proper voltage should be whatever voltage is being supplied by the battery.

 

how does the light flash to tell you rich/lean and open/closed loop?

 

The field service indication has to do with the timing of the flashes. If the light flashes more than twice per second, you're in open loop. If it slows to about a flash per second, you're in closed loop. If the light is "on" more than it's off, than you are either rich or lean, and if it's "off" more than it's on, than its the other end of the a/f ratio, but I don't remember which way it goes for that. I never could tell when I hit closed loop, since it always appeared to be the same to me. Maybe now that it's not 40 degrees outside and my coolant fan isn't running all the time, I could tell you...

 

How come everyone says that if you start the engine with Aand B crossed it will fry the ECM?

 

I think it might have something to do with a voltage spike of sorts that occurs when the engine first starts and the alternator kicks on. I've done this several times with no problems, yet.

 

why would my alternator go bad after doing this?

 

Read Vaders posts here:

https://www.thirdgen.org/techbb2/sho...d+service+mode

 

I accidentally started/stopped the car off and on for about 30 miles in diagnostic mode. It overheated so I turned it on for the fan and forgot to unplug it since I was so angry and having to limp the car to a gas station.