WizardBlack Posted October 14, 2007 Share Posted October 14, 2007 OK, I have a '77 280Z. I have had it for about 1200 miles so far. It had a lot of screwed up things when I bought is so I have been going through and fixing things up. Some of the things I have done in the past (and it has run fine afterwards): Eliminated excess wiring/components for wipers, radio, heat, rear defrost, EGR, etc. etc. Got a good AFM and tuned it. Set hot lash on valves. It is basically has everything to run (including cold idle) with turn signals, hazard, etc. The only engine thing I have removed is the EGR and the coolant lines running through the little block under the bi-metal device that is powered and varies idle air. Anyways, it has decent dual electric fans, 280ZX alternator, and a relocated battery. The ground side was only 16" long and run to a bolt on the rear of the chassis. The power side was (and is) run under the carpet and up to the starter post. My voltmeter was always showing about 16 volts (basically pegged) while running and sometimes it would light up the 'charge' light. I left the electric fans running (ignition on) with the car off for about 10 minutes the other day since it likes to creep up on temperature after it shuts off. When I got back to the car, the battery was dead. I jumped it and drove around for a while but I think that was the last hurrah for the battery. It drove with a jump a couple times OK and then the last time it was popping and sputtering the ~1/2 mile drive home. I went and bought 2-gauge welding cable (very pliable and high thread count) for a new negative line and bought an Odyssey PC680. I mounted the new battery (after charging) with the existing lines and drove it to my shop. It ran fine on the way there. Once I got there, I ran the ground wire from the battery up to the engine side of the firewall. I hooked in right where a harness ground wire was so it would be directly linked to the battery. I also ran a new 8 gauge wire from that point to the starter bolt. The ground wire for the fans is also hooked up to that same point. I thought I was on a roll so I looked over on the driver's side by the clutch master cylinder. On that side, the harness comes through the firewall. In that harness, it has about 5 ground wires that are bolted to the chassis there. I left those alone. It also has a 12 gauge power wire that was routed back through the firewall and under the carpet to the battery in the rear of the car. I eliminated that run and just ran it across the firewall and hooked it up to the starter post as well. It should be the same exact thing; just cleaned up a bit. I am not sure what those grounds and the one power wire are for, but I figured it was ECU grounds and main power to the ECU (which is obviously on all the time). I dunno. I started it up and it started fine. Felt at least as smooth as it was before but I didn't do much since it was cold. About 60~90 seconds in it just shut off like I had turned the key off. I tried to re-fire it and nothing is responsive. No radiator fans (which come on with ignition), no fuel pump prime, no hazards, no turn signal. It is completely silent. I still have 12.08 volts on the battery. I tried about a dozen times. ONE time it has a little sign of life but acted like the battery was dead. I clicked it off and back on and it was back to dead. Stone cold dead. Now, I removed most of the glass fuses in the past for things I didn't need but I rechecked the ~7 that are left and they all have less than 1 ohm of resistance. The one thing I do see is that the voltmeter has always reacted when I press the brake pedal. Even with it off, the volts drop while I have my foot on the brakes. I don't know it that's the norm or not, but there it is. So, anyone have some ideas? Maybe the internal voltage regulator fought a losing battle when the fans were on and the car was off; thus frying it? Maybe it finally burnt out and that's why it won't start? (I thought you could run a car without an alt, but maybe with it on there and fried it is doing something). I looked at the wiring job and it seemed pretty straightforward. Hook two wires together; twice and otherwise it's a direct plug-in. I noticed back a month ago that the T-Connector on the alternator was off and I plugged it back in. I always check the connections now. Anyways, thanks in advance... Mark Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted October 14, 2007 Share Posted October 14, 2007 Dirty battery posts and/or bad grounds. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 15, 2007 Author Share Posted October 15, 2007 Dirty battery posts and/or bad grounds. Brand new gold plated battery posts. Brand new ground. UPDATE: I found that the ground wire running from the alternator back through the harness was cooked and bare in several spots. I pulled it all out and replaced that section. It still will not fire but at least now fans and pump come on, etc. I am hoping the voltage regulator is shot. I will have it tested and see what's next to be fixed. Quote Link to comment Share on other sites More sharing options...
ktm Posted October 15, 2007 Share Posted October 15, 2007 Was it the ground wire or the battery sense wire? I had something similar happen. I COMPLETELY cooked the battery sense wire. I mean there was NO insulation left on it from the plug all the way to where it hooked up to the power wire from the battery (at the starter). Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 15, 2007 Share Posted October 15, 2007 Check the fuseable links. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 15, 2007 Author Share Posted October 15, 2007 Was it the ground wire or the battery sense wire? I had something similar happen. I COMPLETELY cooked the battery sense wire. I mean there was NO insulation left on it from the plug all the way to where it hooked up to the power wire from the battery (at the starter). It was the 10 gauge black wire that is definitely ground. Several other ground wires route through and connect to it. Moving backwards, the first ground is the one that bolts to the side of the engine block. Then two to I don't know what. One looks like a test connect for something. It's a four pin connector with just a plug on it. Eventually it moves back to another ground bolted to the fire wall, etc. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 15, 2007 Author Share Posted October 15, 2007 Check the fuseable links. OK, I have two fusible link boxes. Each one has a pair of links in it. One is totally missing, shot, melted. It looks like they almost (GASP) welded a spot to combine the two, BUT that one smokes if I leave the headlights on, so I thought it was that. I don't drive the car at night; at least until I have gone through and fixed that. Believe it or not, that was lower on the list to do (based on need). LOL. I think when I looked at the wiring stuff for the alternator that the other 3 were fusible links. They look but, but I don't know much about fusible links. I thought they kinda melted or at least 'seared' when they failed. NOTE: The starter doesn't do anything, but IIRC the fans continue to run. Quote Link to comment Share on other sites More sharing options...
george.bryant Posted October 16, 2007 Share Posted October 16, 2007 Sounds like your wiring is overloaded? Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 16, 2007 Author Share Posted October 16, 2007 Indeed, but how is the question. Can the voltage reg inside the alternator do that? Some sort of failure or short that fries the ground wire? If the starter ground wire was somehow not connecting well would it run through the alternator ground and fry it? Quote Link to comment Share on other sites More sharing options...
ArnZ Posted October 16, 2007 Share Posted October 16, 2007 The fusible link that smokes when the headlights are on should be at the top of the "TO Do" list. I would first concentrate on trying to get everything working like it was without the car running. If your meter has a continuity mode, test the fusible links. You can always make a temporary fusible link by using a ATC fuse with some female spade connectors and electrical tape. I would reconnect your 16" ground and make sure the ground point is clean, wire brush any paint, dirt etc. Don't take any wires for granted, "I know for sure that wire is a ground" has bitten me in the butt many times. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 16, 2007 Author Share Posted October 16, 2007 The fusible link that smokes when the headlights are on should be at the top of the "TO Do" list. I would first concentrate on trying to get everything working like it was without the car running. If your meter has a continuity mode, test the fusible links. You can always make a temporary fusible link by using a ATC fuse with some female spade connectors and electrical tape. I would reconnect your 16" ground and make sure the ground point is clean, wire brush any paint, dirt etc. Don't take any wires for granted, "I know for sure that wire is a ground" has bitten me in the butt many times. I peeled the ground back all the way to the firewall. It also branches off and bolts to the block with a ring terminal (just on the side, not to a sensor or anything) and also to a toothed ring terminal bolted to the firewall. I followed it all the way through the firewall and back to the ignitor module (or whatever you call it) and it plugs into the end; IIRC it was labelled as a ground. Anyways, I have a theory. The grouning wire (assuming it is indeed that, of course), was evidently rubbing against the frame and may have been grounding to the frame right at that point. I think it also rubbed against all the 8 gauge power wires running to and from the fusible links. I think it arc'd across and ground out to the chassis and the engine, etc. That would explain why only the certain section of the ground wire was cooked and seared, etc. The 10" leading up to the alternator and the engine ground are fine. It's only the ~2 feet running from (just in front of) the firewall to where it leaves the channel it is resting on on the frame rail and shoots across to the block and alternator. That is the same area where it is rubbing on the frame and rubbing against all those power wires. There are (50 + 50 + 50 + 80 = ) 230 amps running through those wires. I went to atlanticz.ca and looked through their fusible link stuff and bought some fuse distribution blocks on ebay to redo most of that section. We shall see how it goes. I will update when I have it done. Quote Link to comment Share on other sites More sharing options...
Daeron Posted October 17, 2007 Share Posted October 17, 2007 Maybe I am missing something here.. but how does a ground wire short out against the chassis and burn? Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 17, 2007 Author Share Posted October 17, 2007 Maybe I am missing something here.. but how does a ground wire short out against the chassis and burn? Sorry to be unclear. It rubbed raw against the power wires and my reasoning that only 16" of the ground wire was burned was because the other end of the burned section had rubbed raw on the chassis. That was the closest ground point. I also got it started. It will shut off if I wiggle the fusible links and then I can start it again if I let go of them. They also get almost too hot to touch. New parts are on the way so I am going through it all now to tear stuff out and redo it as they FAQ's show you on here and atlanticz.ca. Thanks again! Mark Quote Link to comment Share on other sites More sharing options...
spacecase70 Posted October 20, 2007 Share Posted October 20, 2007 I hate to say this man, but.... TIME FOR A REWIRE JOB! Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 21, 2007 Author Share Posted October 21, 2007 I hate to say this man, but.... TIME FOR A REWIRE JOB! LOL yeah. You aren't kidding. I am doing just that, actually. Eliminating the fusible links, eliminating superfluous wiring (ditched A/C, P/S, wipers, heater, etc. etc.), upgrading the headlights, etc. Once I get my Megasquirt/EDIS-6 all set up I will ditch the OE harness for the most part as well. Quote Link to comment Share on other sites More sharing options...
spacecase70 Posted October 22, 2007 Share Posted October 22, 2007 I hope your install goes well for you, and good luck and happy Z-ing!!! Quote Link to comment Share on other sites More sharing options...
happynukes Posted October 23, 2007 Share Posted October 23, 2007 had my 81 shut down in the middle of traffice because of a stupid red fusible link sounds kinda like the same deal check those first before you get crazya nd start ripping crap out that you might need later did that and mow one the headlights goes on and off when i hit the high beams never got it to go back good luck hope you finid your bug Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 23, 2007 Author Share Posted October 23, 2007 had my 81 shut down in the middle of traffice because of a stupid red fusible link sounds kinda like the same deal check those first before you get crazya nd start ripping crap out that you might need later did that and mow one the headlights goes on and off when i hit the high beams never got it to go back good luck hope you finid your bug Bah, I have done full wire-in standalones and whatnot before. I fear no wiring. I more fear factory wiring catching on fire or failing somehow. Regarding fusible links, yeah they tend to get sensitive to wiggling when they are getting long in the tooth. Or so mine do, anyways. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted October 28, 2007 Author Share Posted October 28, 2007 Update. I have installed a car audio fuse distribution block to replace the fusible links and bought 2gauge and 4 gauge wire to replace the big wires for starter, alternator and battery negative, etc. The car is running good again. Next step is to replace the headlight wiring and then follow up with a new chassis fusebox (under the dash). For the headlights, I am going to pull direct from the battery and relay/fuse it with a toggle switch to control it. Not sure but I think I'll need a 3-way switch to deal with LO/HI beam situation... Quote Link to comment Share on other sites More sharing options...
happynukes Posted October 29, 2007 Share Posted October 29, 2007 stupid fusible links!!! reccomend rewiring the whole thing, thats what i'm gonna do with my 76 now that its almost bare bones. Quote Link to comment Share on other sites More sharing options...
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