Can anyone tell me how to test the ECM in my 1986 Fiero 2M4. I need step by step instructions. I am pretty new at this. When I turn the key on, the SES light does not come on, but it is OK cuz I checked it. Also I do not hear the fuel pump engergize ( it is ok too, cuz I tested it as well and put in a new Fuel pump relay) The engine turns over, it just doesn't get any gas.

As I understand it, the SES light IS the test for the ECM. It should come on when the key is first turned to ON. How do you know the light is good? Have you tried pulling the codes?

You would probably need specialized equipment to actually test one off the car.

Hi there,
Are you familiar with the ALDL test? The plug under the cigarette lighter cover? If not, take the black cover off the the center console (has 2 T15 screws) and locate the black ALDL plug (right next to the cig socket.) put a jumper wire across the 2 lower-left pin sockets. Then turn the key to "run" (but not "start"). Watch the SES light. If your ECM is bad, you should get a code 54 (5 blinks of the light, followed by a pause, then 4 blinks).

Someone please double-check me on this, but I think this is the right info. Doing this from memory, don't have my Chilton's manual in front of me. Or my car either, for that matter. So I hope this is correct.

They're right, light should come on with initial key on position, if not, it's like 7 screws on the back of the cluster to remove panel and gain access to the light bulbs. You really should be able to hear the fuel pump prime up for two seconds with initial key on, listen carefully.

Before we get too far ahead of ourselves, be sure to double check all of the fuses. I can't see those stupid little things so I got an electronic tester for $6 bucks with some spare fuses at the auto parts store, best little investment ever, no doubt whatsoever now if a fuse is good or bad.

Here's a picture worth a thousand words on how to jump your ADL,



See how I jumped the ADL with a paperclip?

Yes, that's my dirty looking console, this picture looks better.



Good luck, let us know what you find, ok?

EDIT,,,

Almost forgot, here is the forum engine codes & instructions page.
https://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

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jetman
Silver 86 SE 2M6 4-speed, with "check wallet light"

[This message has been edited by jetman (edited 12-27-2007).]

yes, check the fuses first. also, I am not sure what year they started this, but my the positive battery post, near the c500 connector, there is a inline plug on a + line, this is used to drop power tot he ecm for a reset. check/reset that connector.

here is alink to the wiring connector at the ecm:
http://home.att.net/~subzero350/

1986 Fiero 2.5 TBI should be the one for you. you can use that to test that you have power and good grounds at the ecm connector.
you will need to pull the console armrest and glove box assembly to get at it. be sure they are firmly seated in the ecm. you may want to disconnect the battery and pull and re plug those connectors if in doubt.

other than the ses light coming on, there is no practical way for the average person to test an ecm.

The light came on when I applied 12v to pin G on the ALDL. So I know the bulb is good. I can't pull any codes because the light won't come on when I turn the key to the ON position.

quote Originally posted by Hudini: As I understand it, the SES light IS the test for the ECM. It should come on when the key is first turned to ON. How do you know the light is good? Have you tried pulling the codes? You would probably need specialized equipment to actually test one off the car.

Might try this and see if it tells you anything... I have done it but is in the service manual..

quote Originally posted by dextersbones: Thanks for that information and the photo. They say a photo is worth a thousand words. Can you take a photo of the c500 connector for me to show me what it looks like and its approximate location? How do I reset the connector? Just unplug it for 15 seconds? I have checked the fueses, but will do it again with a multimeter. Thanks for the link but which wiring connector should I be looking at, the white one or the black one? Can I put a probe onto one of the terminals on the connector to determine if there is voltage there? If so, which terminal should I be testing?

ok, can;t get a pic of c500 now, pouring rain here. I can tell you where it is very precisly tho.
remove the vent cover over your battery. there is a small flat area on the fenderwall between the battery and the strut tower.
on the falt part of the fenderwall is a screwed together block connector with a large harness going to it. it is held together with bolt. that is the c500 connector. you don;t need to do anything there, you just need to follow the harness from it.
follow the harness towards the battery, and there should be a loop of wire with a snap connector hanging out of the harness. this is the ecm power line. I believe the wire will be orange. As I said, I am not sure of what years had that connector, but I think 86 did.

Now for the ecm connectors. if you reference that link, it has 3 files in it, look at the white connector diagram, that will refernce the connector pin locations. you will see 2 orange wires going into pins 10 and 15, those should have 12v as long as the battery is connected.
Pin 13 goes to a balck wire that will be attached to a loop to the sheet metal on the console right near the firewall, be sure that ground is clean and good.
pin16 should have a pink/black wire, and will have 12v only when the ignition key is on, and the ecm fuse is good.

that should cover the ecm having basic power at the unit. if there is a problkem with any of those, you will need to work them back to find the problem. you will need to pull the console to get at the ecm, it is located on the firewall behind the glovebox.
It was the black and white connectors at the ecm I was suggesting you replug.

[This message has been edited by tjm4fun (edited 12-27-2007).]

I found c500 and checked the link you refered to with a voltmeter... I read 11.4 v off the pin. I suspect that this is low because I have run my battery down trying to start the car. Thanks for the additional information.

I want to thank everyone that responded to my questions. I finally found the problem. One of the wires that contains a fuseable link located below block c500 had broken loose from the connector. The connector bolt was so badly rusted that I had to cut it off and replace it with a new one. Once this was done, the car starts and runs great.

BTW I have owned this car since I bought it new in Vancouver in Dec 1985 and I still love to drive it. It has 160,000 km on now. It was a mid-life crisis sort of thing which I have never regreted.