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Old 04-11-2011, 06:24 PM
mean s15
 
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87 s15 carbed v8 swap, wires that supply lighting

Originally a 2.8 tbi. Anyway I have carbed 350 in now, I hooked all my wires I needed without zapping myself, most every thing works like starter, dash lights, dome light. Here's the thing without the key on my turn signals work, and I have no parking lights or headlights in the front, parking lights in the back work though and my battery light is on constant. Large pink wire to hei distributor hot all the time, red wire to alt for fuse panel, another red wire from the fuse block on the firewall goes to starter, purple wire to s side of starter. Oh and there was a brown wire from alt to indicator light. Anybody think this is wrong? Searched everywhere on the net for input. Maybe a bad ground I don't no.
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Old 04-12-2011, 03:33 PM
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Before the swap did everything work OK?
Does the engine run?
All the things you mention are chassis electrical except the engine start wire (purple) to the starter.
First thing is go over all the wiring and compare it to the schematic.
Check the ignition switch and headlight switch for proper connection.

vicrod
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Old 04-12-2011, 04:39 PM
mean s15
 
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electrical

Just found TDC on the engine today, didn't run yet my battery died but everything sounds ok so far, before I found TDC timing was way off and was shooting flame. Something not right all lights worked before the swap. The haynes manual didn't really help. There's the braided ground strap on the firewall that broke that goes to engine block pryer to engine removal would that throw me off? Thanks for the reply
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Old 04-13-2011, 11:17 AM
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Yes, the ground strap is very important. Engine to body, engine to frame and frame to pickup bed. Good solid, clean connections are a must.

vicrod
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Old 04-13-2011, 12:11 PM
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lights

first check all fuses.
if you have a test light check for power at the lights. if you have power there with the lights on, but the lights don't work, then you have a ground issue. up at the battery there should have been a cable for ground that goes to a good clean ground on the engine, it usually has a smaller wire, that is part of the cable, that comes off and is screwed to the rad support. I have seen those screws come loose or corode so the ground is connected at the rad support but it doesn't make contact, so no ground. take the screw out, clean the connector and the rad support where the screw goes, and then put it all together nice and tight. if the screw won't tighten up then the hole is too big and you will need a bigger screw. there should also be a ground strap on the firewall, as you mentioned, so the cab gets a ground. since the cab isn't a good connection to the rad support or the engine, because both those parts are sitting on rubber, you can see why there are a lot of different places where a ground is required. also the box should have a strap on it for the tail lights, but they may be grounded to the frame back there. a good wiring diagram will usually tell you where the factory grounds are located.
just out of curiosity, did you mean that the pink wire to distributor is hot all the time, even with the key off? it's not supposed to be hot with the key off, or you wouldn't be able to shut the engine off. do you have a wiring diagram for that truck? wht year and model is it?
dsraven
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Old 04-13-2011, 01:03 PM
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wiring

here are some of the key wiring colors and where they went on the s15 truck with 2.8 (before the swap).you will need to connect the right wires for the 350 to run and charge properly. the alternator and starter wiring should stay the same.

alternator:
- pink with black stripe, pin # 39 at alt plug, should go to the ac compressor relay, oil pressure relay, instrument cluster and convenience centre.
-brown, pin #25 at alt plug, should go to the instrument cluster and fuse block pin #A.
-red, pin #2 at the alt plug, should go to the junction block on the firewall, and to the battery. also goes to the pwr accy circuit breaker and the ign switch pin batt1 and pin batt2. probably only one wire at the alt, but it splices into a "Y" and another wire is added to it in the harness somewhere.

starter:
-purple, pin #6 at the starter, goes to the ign switch start position.
-large black cable, position #2, goes to the battery pos.
-red, position #2, goes to the junction block on the firewall.

distributor:
-pink, pin #3 in the plug at distributor, goes to the ignition switch, hot in run and start only, also goes through a connection to the turn and b/u fuse.

try unplugging the alt plug and see if the signals work only with the key on after that. maybe a backfeed from the alt is powering up your ign switch etc? is the charge light on even with the key off? maybe a faulty alternator.
start with the lights and get them working. probably a bad ground by the sounds of it. the ground wire on the rad support was probably disturbed during the removal and install of the new powerplant.
then fix the firewall ground strap.
then see what you still have that's not working properly, with the key on and off.
hope this helps, otherwise grab a wiring diagram from somewhere and start doing continuity tests.
dsraven
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Old 04-13-2011, 03:31 PM
mean s15
 
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It's a 1987 gmc s15, carbed 350, hei ignition. I started the truck lastnight it shuts off fine. The batt light is on as soon as I hook the batt up. I do have the striped pink wire to the alt wrong, its hooked to the alt post not the harness one. Headlight switch turns on the dash lights but no head lights except for one highbeam. I'm going out to check my grounds tonite. Oh and would that braided ground strap make my engine run any different? My brother thinks it does. But I will fix it anyway. Thanks and I appreciate all your guys help.
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Old 04-13-2011, 03:51 PM
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striped wire

if you connected the striped wire to thethreaded post on the alt then you would be feeding the fuse box from the battery through that connection. that could also be why your charge light is on all the time, it's like having the key on with thengine not running.
that braided wire could have a bearing on how things run, it should get a good engine ground, but maybe not such a good body ground for the cab.sounds like your light problems are ground related. each light has a seperate ground wire that goes to the rad support, under one of those screwsI talked about earlier. check there first. it doesn't hurt ot clean it up even if it is working at the moment. also check the plug on the back of your light, they corode too.
dsraven
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Old 04-13-2011, 05:59 PM
mean s15
 
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Were all fixed up guys! The pink striped wire fixed all my problems. Everything works. Thanks everyone
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