Just bought a 85 K5 Blazer from a guy who had started to half ass restore it. Has new vortec 350 with edelbrock 350 electric choke and single wire alternator. Has stock front runner GM accessories. The issue is I have all the stock connections still on the firewall as well as the emissions stuff still. The engine side of the harness is a mess so I got a new engine side harness from the firewall from brothers. I want to connect everything right without hacking it all up or using wiring that I don't need. It has HEI distributor and running dual electric fans on the radiator. Also has AC on drivers side. So that being said I have a fresh harness ready to run everything but dont have a reference to go to the right things from the new firewall harness. I'm sure some of you experts on here can help. Any help would be appreciated. want to get rid of all the emissions crap I don't need as I live in south texas and don't need it. Thanks everyone.....
CK5
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Help what is what - Wiring
- Thread starter JCP
- Start date
Look here: https://67-72chevytrucks.com/vboard/showthread.php?t=545416
Wiring diagrams for most Chevy trucks
Thanks Wes, Its a factory reproduction harness. The issue is I'm not sure what wire to use with the Alternator, AC Compressor, Electric Choke, Electric Fuel Pump, and My electric fans.
Well the factory never had electric fans. I wouldn't expect a factory harness to have those connections. 85 was still carbureted and still had mechanical pump, prob no provision for electric fuel pump. Also an 85 would have had a computerized carburetor. which requires more wiring than the Edlebrock. Not to mention a MAP and Baro sensors, o2 sensor knock and est. We need to know what "factory" loom you have ?
AC will have black 2 wire plug 1 dark green and 1 black wire. Choke coil will be 1 wire plug lt blue. Alt will be a 10 or 12gauge wire to 1/4" stud and 2 wire plug smaller red wire and brown.
AC will have black 2 wire plug 1 dark green and 1 black wire. Choke coil will be 1 wire plug lt blue. Alt will be a 10 or 12gauge wire to 1/4" stud and 2 wire plug smaller red wire and brown.
Computerized carb was only on CA trucks. The only wiring for the carb on 49-state trucks would be the A/C throttle kicker and that 2-step accelerator pump thing. But likely the Edelbrock has neither. It would have the ESC knock retard box in front of the glove compartment, with a weatherpack connector going to the ignition module in the distributor.
Is the harness for an '85 gas truck? Does it have loom on it, branches predefined and connectors on? Things should be straightforward, with things only plugging in one way. The biggest question will be where the harnesses should be routed.
As for "emissions crap" it can be difficult to cleanly delete some of the stuff. If you had the factory quadrajet, you could get things back to original, but with an aftermarket carb you're forced to make some changes. Don't assume that because something is called "emissions" that it's hurting the performance. I remember years ago somebody removed like 80% of the vacuum hoses and gadgets because *something* in that mess was making it run bad. Afterwards the original problem remained, but now the fuel economy was much worse because there was no vacuum advance. I'm just saying you have to understand how all of those parts interact before you can make good decisions about how to change the setup.
The harness taped to the vacuum hose goes to the cruise control module. The round thing on a firewall bracket is the "tip in" vacuum switch, which is part of the ESC. That weather-pack you have circled below it should plug into the ignition module wiring (that spark box is under the dash, in front of the glovebox. Chances are that the distributor has been swapped or the module swapped to get by without ESC, but this is also some harness mod that bypasses it.
Do you have the emissions label on the core support? It can shed some light.
Do you have the emissions label on the core support? It can shed some light.
Well the big ball is easy that is a vacuum reservoir for the hvac controls under dash, you want to keep that. the rubber hose (bottom picture) is for a cruise control system that has been removed.
3rd pic down I believe the 4 wire connector is the electronic spark control wiring.
I See the new loom you installed I curious why the choke is not included.
Was this a CA truck ? Vin search will help with that question. Did it have a 700R4 factory ?
Will get back to you solution for choke. couple ways to do it. memory is fuzzy need to refresh.
3rd pic down I believe the 4 wire connector is the electronic spark control wiring.
I See the new loom you installed I curious why the choke is not included.
Was this a CA truck ? Vin search will help with that question. Did it have a 700R4 factory ?
Will get back to you solution for choke. couple ways to do it. memory is fuzzy need to refresh.
The Blue wire with black tape in 3rd picture near the tip in switch, where does that go. On the top side ?
Down by the oil filter, threaded into block is there a sensor/switch with 3 wires ? If so the lt blue wire is the factory choke coil wire. the other 2 wires should be pink with white trace and dk blue.
Where are the 3 larger red wires going ? green circle
So I am thinking the red wires do go to starter and alternator. Two of the red wires should have Fuseable links and 3/8" ring terminal. These 2 need to go on the starter battery cable stud, and will be hot all the time. They provide power to the ignition switch and horn, head lamps, courtesy lamps, cigar lighter, and alternator battery terminal. Also the any normally hot cavities in the fuse box.
The 3rd red will got the alt with 1/4" ring terminal and should have a rubber boot. The purple wire in that bunch will go to the start terminal on the solenoid with #8 or #10 ring terminal.
One thing to check when connections are made with the 3 red power wires is that the junction block on the fire wall has power. Not sure what this new loom has going on but that junction block should be part of it.
The 3rd red will got the alt with 1/4" ring terminal and should have a rubber boot. The purple wire in that bunch will go to the start terminal on the solenoid with #8 or #10 ring terminal.
One thing to check when connections are made with the 3 red power wires is that the junction block on the fire wall has power. Not sure what this new loom has going on but that junction block should be part of it.
