Hi guys, I'm at a total loss here. So I have myself a 1988 Honda Civic SE with a swapped 1.6 SOHC ZC, when I bought it, buddy told me the alternator was dying, and that's why the battery light was on. At my shop, we tested the alternator and it passed with flying colours! So we tested every wire from the OBD0 plug to the battery, apparently nothing broken there. So we figured it must be the ECU, I went and picked one up, and tossed it in there. Still no charging the battery. So I went and checked every fuse, in the engine and under the dash, replaced a couple and nothing. We unplugged the "load module" wire, and it started charging again! Although, after driving with the new ECU my engine's revs are all off, and I get misfires above 4k revs. Another issue occurred as well, my day lights no longer work anymore, and after checking the fuse for the lights it was fine. The next morning my battery was still dead so I'm starting to get very frustrated. I want to put the old ECU that was tuned for my ZC back in but there hasn't been any point yet since it's been sitting in my driveway dead for like 2 weeks. I really don't know what is wrong with my car and I would love some help! Thanks!

 

check that the big alternator fuse in the engine fuse box is not blown, should be 80A or so

with the car on a cold start, with the idle above 1500 rpms, test the battery voltage, should be putting out 14 volts

if it charges good, wait for the car to warm up and test again

if it's still charging good, test for a parasitic battery drain

 

Consider the ELD, found in the underhood fuse box (passenger side strut tower).

Not for our gen, but one of the best explanations I've found so far:
https://www.civicforums.com/forums/2...-detector.html

See also, and note that a bad ELD may be related to a hosed voltage regulator in the alternator:
https://honda-tech.com/forums/honda-...ector-2753984/

Google ftw! And put your old ECU back in before you break that poor ZC.