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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
If you are looking to install into the car one of the easiest ways to identify the plugs is to find a couple odd shaped ones to match up under the hood so you get an idea of the route the different parts of the harness have to go, then start following the wires. Since almost all the plugs are different it can actually come together on its own easier than you would think. Especially since the wires are basically just as long as they need to be and not much extra.
Some of the wiring is a bit on the crispy side, broken, faded, etc. I'm hoping to rework it a bit. Maybe lengthen some wires marginally to aid cable management, etc. I'll also need to get a few pigtails.
I laid it in the engine bay earlier to help figure some things out. Of course, all I have at the moment is the engine, transmission, and water pump in the bay right now, so it didn't help overly much. I need to paint the brackets and pullies still. Its been rainy so I thought I might be able to get the harness ready to go while I wait for a good time.
Chances are fair there are a couple relays by the brake booster. On the later cars the wiper washer pump and wiper motor are wired through the engine harness. Usually the HVAC harness will tap in somewhere on the passenger's side.
After some investigation, I think N is for the wiper motor.
Thanks for the assist, guys!
In other news, the starter wires are either burnt off or have been cut (R, S, T, U). Does anyone know offhand what gauge wires these are? So, where specifically they go?
U & T go to the terminals on the starter, I believe. There's another wire that comes off of U that I don't know where it goes. I also have no idea where R and S go. Do they go to the same terminal as S?
Beg, borrow, or steal copies of the wiring diagrams from the 1984 Firebird shop manual. For that matter, the diagrams back that far kinda start to slip into the era when they were line drawings and everything starts to blend in... Maybe even an Alldata or Mitchell diagram would be better...
Anyway, the starter wires are going to be fusible links. You'll want to replace the aged links with new fusible links. Think of fusible links as extra heavy duty in-line fuses. They power everything in the car, with the positive post of the starter acting like a junction block. They need to be repaired right, with new fusible link wire, or you could have an electrical fire, etc on your hands.
Left rear is the Electronic Spark Control box, part of the knock sensor system. The far right is a MAP, BAP, etc depending on how it's connected, etc, basically a pressure sensor the computer uses to try to adjust the carb. The thing in the middle top, is the switch for the cowl induction.
The other two are relays. The fan on the HO is electric right? One probably is for that... Same question on the fuel pump, the HO is electric right?
It does indeed have an electric fan. I switched over to an independent controller, though, so I can probably tuck that away.
Most L69s, as far as I've read, were retrofitted with an in-tank electric pump. My car, however, was not. When I pulled the tank there was no in-tank pump (or wiring for one, just two wires).
Just to add; I did a serpentine swap also when installing the new engine, so I need to iron out the changes for the Alternator and AC system. It appears that I need to switch to a newer 3-pin pigtail for the alternator, rather than the 2-wire. I haven't really looked into what needs to change with the AC yet.
On a side note, the Alternator terminal is awfully close to my valve cover. I'd say it's only got about 1/4" to 3/8" clearance. Should I be concerned? I feel like I should insulate this somehow.
The front and rear halves of the alternator case can be re-clocked by loosening the case screws and carefully turning. Just don't get them too far apart or the brushes will pop out.
The other frequent cause of problems is some remanned alternators have a 90* adapter on the charging post. In some cases the adapter can be removed to gain some clearance.
The A/C compressors all have a 2 pin clutch and some have a switch in the back. The clutch may just require a connector change. The switch may or may not need to be intalled or connected, depending on how the system is configured.
I soldered in new 14-gauge fusible links on R and U. I assume that these used to be connected at the O-shaped terminal previously (unsure though, since they obviously were broke, melted, cut, or whatever separated them), so I'm guessing they go to the same terminal.
Just to make sure I don't melt anything down or kill my ministarter - R & U go to the Motor side terminal, T goes to the Switch terminal, and a straight run from the battery goes to the BATT terminal. Does that sound right? Would anyone happen to know what gauge\length I need for the battery cables? I'm guessing 2 AWG but I'd like to be sure.
Additionally, with the alternator cable; the way it was hooked up before, was that the 2 wire harness plugged into the alternator, and then a presumably 12v wire came back out of the harness and screwed onto a terminal on the alternator. Do I still do that with the adapter harness? Or should that be a separate run to the battery? Or both?
Edit: Does anyone know where the heck S is supposed to go? Seems like it angles back upwards but then it was obviously destroyed. Fan relay, perhaps? It's the same gauge as R.
Thanks for all the help, guys. For some reason I'm just having a hard time wrapping my head around the wiring.
Additional questions; is it unsafe to test the fan by hooking it directly up to a battery rather than through a relay? I just want to make sure it works before I start wiring everything up. Also, is it just the upper fan mount that hold the radiator and AC condenser in place? Radiator sits in quite tightly, no problem. AC condenser its sort of wobbly though.
I'm starting to suspect that this harness isn't original to the car. Things just don't match up.
The tach wire is white, rather than black (according to the 84 TA L69 schematic). There's a 3 wire oil pressure sender\switch (N) with some other wires coming back out of it to go to God knows what, rather than the 1-wire that I was looking for.
Just to update, I did get everything ironed out with wiring, aside from the HVAC system, which leads into my next project.
My HVAC system is all from a 90 Formula. Obviously, there is some mismatch from my 84 harness (I'm assuming it's just power since the wiring in question comes from the engine harness) to the 90 HVAC harness. I do have pigtails from my old 84 HVAC harness. I've done some searching, but I'm really only finding 4th gen swaps. It's possible my search-fu isn't strong today. My thought is to snip the 90 pigtails and solder in my 84 pigtails so that it matches the rest of the harness.
I'm waiting for the weather\pollen to balance out a bit so I can get back to painting, so I figured this was a good side project to work on in the meantime.
06-16-2017, 06:27 PM
