Producing "No Spark" symptoms- ECM bad or?

[J-Roc]

Hi all!
I'm currently working on a friends ride. '91 Galant GS. It cranks over but produces no spark. I took off the cap to the dizzy , cranked it over, and the rotor turns, so its not the timing belt. My friend is getting the coil tested today, but if that turns out OK, then what next? I've been searching on the site and it seems that these ECMs go out alot on these cars? Where is the ECM located on a '91? Behind center console or pass. side kick panel? Does the ECM control spark to the coil? Whats an easy way to tell if the ECM is functioning properly? Thanks all.

[kenjan]

Hi all!
I'm currently working on a friends ride. '91 Galant GS. It cranks over but produces no spark. I took off the cap to the dizzy , cranked it over, and the rotor turns, so its not the timing belt. My friend is getting the coil tested today, but if that turns out OK, then what next? I've been searching on the site and it seems that these ECMs go out alot on these cars? Where is the ECM located on a '91? Behind center console or pass. side kick panel? Does the ECM control spark to the coil? Whats an easy way to tell if the ECM is functioning properly? Thanks all.

My guess would be the ECM. The ECM on the Galant is somewhat fragile, so it would be more likely at fault than the coil. The easiest way to tell if the ecm is at fault is to retrieve the error code, see here for details. Basically, locate the driver side fuse box and the number one fuse is the the MPI relay, which is the diagnostic port. Stick a electrical buzzer (Radio Shack #273-055 $2.49) in it and it'll start giving off pulses. see the link above on how to decipher the error code, he explained it pretty well.

[J-Roc]

Sweet! Thanks for the link kenjan!!! :thumbsup:

[J-Roc]

So where exactly is the ECM located? :?

[jeucken]

So where exactly is the ECM located? :?

ECM is behind the glove box, the one behind center console against the firewall, is the tcm, which controls the shifting points. it is actually held by three bolts, two against the firewall and one on the floor close to the radio.

[J apmetal]

I pulled my ECM today [it needs those notorious caps changing] and it's exact location is behind the glovebox, bolted to the base of the A-pillar with 3 yellow plugs entering it from below.

there's a bolt at the bottom near the front, and a nut at the back [again on the bottom] I found it easier to unplug the cables first to allow access to both of these. Then the unit should lift out slightly [to clear the captive bolt at the 'front' end of the unit, where you took the nut off] and slide down to the floor and out


The whole process took me about 15 minutes; Hope this helps !

[J-Roc]

Thanks for all the info everyone! I plan to go to his house and check for codes with the buzzer trick. I'll let ya all know what I find...THANKS again all!!!

[J-Roc]

Okay guys,
This is what I found. I bought the little 12V buzzer from Radio Shack and headed down to the house where the ride is. I first checked all of the appropriate fuses to make sure none were blown. Then, I hooked up the buzzer to the 2 terminals in the diagnosis port and got nothing. So, I grabbed my digital voltmeter and begin checkin voltage. It's at 10.4 volts or so- CONSTANT. Sooo, I look at the chart that I printed out and it says that a constant signal means that you got a fried ECU. Also, when I turned the key to the ON position I did not hear the fuel pump at all. Not a sound from under the hood or out back near the tank. I took out the ECU in question and opened it up to have a look-see. Upon inspection I noticed that near the middle of the circuit board, there looked to a small battery looking thing appearing burnt. Surrounding the 'battery' was a dark brown, sorta burnt looking. The area loooking to be burnt was only about an 1/8" or 1/4"-about the size of an eraser at the end of a pencil. From these observations, would it be safe to say that the ECU is toast?


P.S.Why wouldn't the lil buzzer go off when I touched the 2 terminals? I checked to make sure it worked by connecting it to the battery. Hmm weird....
:?

P.P.S. Don't forget to vote!

[ken inn]

check out the post above, go to the vfaq site, electrical, first posting is about the caps. if the board smells like rotten seafood, more than likely it is fubar.