Attempting to move my 87GT to winter storage, and it won't start. I'm having a hard time diagnosing the problem.

When I turn the key on, I don't get a check engine light, suggesting the ECU is either failed, or not receiving power (or the bulb failed -- but considering the bulb worked before and the car doesn't run now, I'm considering that coincidence unlikely). I've done the simple step of checking the fuses, all of which looked fine.

Fuel pump also doesn't prime with key on, which is ECU controlled from what I understand. Fuel pump works fine when 12v are supplied to the pin G (?) on the ALDL connector. Car cranks just fine.

Before I start a tear-down, are there any good documents for troubleshooting an ECU? From power feeds through up to the ECU itself? I've got he 87 service manual with diagrams, but still at a bit of a loss on where to start.

Or any general suggestions I should look into?

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Seq

1987 Fiero GT : Information | Gallery

NOTE: If you re-host any of my images on PIP, send me the Image URL and link to this post, and I'll update it.

ECM battery power is supplied by a wire originating at the Battery Junction Terminal, located just below the C500 on the passenger side in front of the strut tower.
The ECM power wire has a disconnect plug a few inches along the wire from the BJT.
Check for BAT power there.
If no power there, fusible link F is bad.
Check ECM IGN fuse with a meter to verify integrity.
Fuel pump relay coil voltage is supplied by ECM from ECM IGN fuse.

[This message has been edited by olejoedad (edited 11-18-2017).]

Here's a pic if you need one.

https://www.fiero.nl/forum/F.../HTML/123455.html#p1

tap ecm by hard. Sometime that will help but ecm is "dead" and need replace.
Save prom in ecm. New/rebuilt ones never come w/ prom/memcal.

Ecm main power is a fuse source. Standby power is fusible link below C500. ECM needs Both to work.

ECM can "die" w/o warning. More so in Fiero because have little air to cool.
See my Cave, ECM Heat

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Well, we finally had an evening that wasn't freezing and/or raining. Grabbed my multi-meter and a flashlight, and dug into this.

Got voltage at the ECM fuse in the cabin with key on, so thats good. Swapped the fuse just in case, since I have enough spares to last the rest of my life.

Tested the battery positive to body, to confirm I had a good ground. Tested the Battery Junction Terminal post, and again got good voltage.

Tested the fusible link, and I didn't get proper voltage. So it looks it's at least the fusible link. Should be easy enough to replace.

Here are some photos of the testing.

As you'll see in the photos:

• Every leaf in the yard fell into the Fiero after I pushed the car into the driveway a few weeks ago, so I've got some cleaning on my todo list as well
  
• My battery seems to be low from sitting for a few weeks. Crank still sounds good, but honestly, I was cranking it a lot a few weeks ago, and it's just sat since. I'd normally have pulled the battery for the winter by now anyway.
  

alt lug is only connection for 2 studs.
If that is too bad then have to make a bus bar to keep 2 studs live.
All on 1 stud often makes problems and why GM uses 2 size of stud and lugs so can't put too many on 1 stud.

Shorten Fuse Link change value of fuse = acts as bigger fuse.
If FL wire have "rust" problems then replace the link. You can't clean FL wire w/o changing value and "rust" or cleaning often acts as "weaker" fuse.

Clean all and coat w/ silicon or brake grease.
Tighten nuts only finger tight. Lube prevent "rust" but allows easy to strip/break small screws etc.

If battery isn't frozen already... (Very likely is or has.) Pull battery and charge now but wait to warm up to normal "room temp."
If possible set charge rate to 3-6 amps max and do not charge w/o checking every 1/2 to 1 hour because need to Watch temp of battery while charging... Warm to touch is normal but if it gets Hot to touch or more then battery is likely bad and stop charging.
Charging doesn't like too cold or too hot batteries. Is part of why many recharge battery packs for laptops etc have temp sensors and charger won't turn on when battery is too cold or hot.
Low car battery will easily freeze and wreck it. Likely have been frozen and expect to replace it next spring/summer. Even AGM like Optima and Gel types hate being low charge in freezing weather.
See my Cave, Battery

[This message has been edited by theogre (edited 11-28-2017).]

The "bus bar" was basically an L shape, with the upper part joining the two studs, and the lower part crimped (and soldered) onto the two fusible links (alt & ecu). It broke at the 90° bend.

The wires themselves didn't appear corroded, so I pulled the old crimp off, crimped on a ring terminal, soldered the join, and wrapped in heatshrink. Unfortunately, my soldering iron doesn't seem to heat very well anymore, so I'll likely pull this apart and re-solder in the spring with a new iron, since I couldn't wet the wires right through.

I cleaned and re-used the existing bus bar, put the new ring terminal on the larger stud, and put the other terminals on the studs they came off of.

Car started first crank, and seems to run great.

Now that it works, time to put it away. Off to storage this weekend.