So Frank(87 244 5-speed manual)has been showing me his battery light the last few days. Battery is next to new so I took off the alternator and had it tested and it failed. Purchased replacement from Car Quest this am and replaced it. Easy as pie. Started him back up ran like normal but the shift up light was on all the time no matter what I did. After about 3-4 mins the car stalled. I restarted and started looking around at what I could have knocked loose or removed and forgot to replace. Nothing I could find. As I searched he stalled again and now will crank but no start. I did knock loose the small white vacuum line going to the engine computer on the pass front fire wall but that had been re-installed with no issues. Any ideas??

Thanks in advance!
John

 

that computer on the right firewall in front is the ICU, ignition control unit, and that vacuum line is used for spark timing (much like an electronic version of an old fashion vacuum advance distributor).

hmm, I believe the shift up light on a stickshift is also tied into vacuum somewhere, as well as the ECU... let me dig up the 1987 240 wiring diagram and peruse it...

hmmm. schema says, the upshift indicator has a control unit tucked under the driver side dashboard to the far left (closed to the door, above & forward of fuse panel), and this gets power from the ignition key via fuse 9... its inputs are the clutch switch, the ignition coil/tachometer signal, and the speedometer, and it drives both the OD and upshift light.

have you checked your battery voltage? fully charged battery should be about 12.6V at room temperature (+/- a few 10ths for warmer/colder than 68F/20C), and if the car is running and the alternator is working, you should see about 1-1.5V more.

the alternator harness is tied into the ignition harness on 1987-88's, its possible when you installed the alt, you disturbed the ICU plug. this plug is a known pain-in-the-$$$$ on these specific years. do NOT rock it if you unplug it, pull it straight out. use a thin probe to GENTLY tighten the contact sleeves in the plug (the pins are in the socket), then apply liberal amounts of electric silicone grease, and push it STRAIGHT on, don't rock. maybe that will do the trick.

make sure your alternator light comes on when you turn on the key, and if/when the car starts, verify it goes out ... some alternators, you need to blip the throttle to get it to go out. when its out, the alternator is outputting voltage, when its on, the alternator isn't. the light itself is a critical piece of the charging circuit.

 

Thanks for the reply... As most mysterious car issues this had a easy fix. I went through all your recommendations as well as rechecked my install and anything I may have touched. Still nothing... then I touched the battery cable and heard some small sparking. Turns there was a short in the smaller wire to the positive battery terminal. It clearly effects fuel delivery. Repaired the short Frank is back on the road. Thanks for your help.