would dash wire harness be installed from factory the same for all engine set ups? for instance. this 86 base firebird was factory lg4. previous owner started ls swap and died in a bike accident before he got very far. I want to install a lb9 with a 87 engine harness and ecm. so would the fuel pump wiring be in the dash's harness?

 

The fuel pump wiring is not part of the dash harness. On the interior side of things it goes from the fuse block down the driver side of the car before going through the rear bulkhead between the rear seats. Dash harnesses did very throughout the years and were different on a multitude of things (engine, trans, options, etc).

 

The short answer is No.

for starters; the factory 86 LG4 dash harness has no provisions (fuses/wiring) for Fuel Injectors. The 87 TPI fuel pump wiring is also a good example; for TPI the fuel pump power wire leads thru the ECM harness and connects to the dash harness at plug C207 PIN 'D",.... but for Carb cars that PIN is empty and there's no wiring in the BODY harness leading back to the pump either. Schematic is a little blurry, but you can see the fuel pump info for TPI.



Worth noting that there is also a change in the way that the ECM displays a CHECK ENGINE light from Carb compared to FI; The light is turned ON/OFF directly by the ECM for FI,... but requires a "lamp driver module" in Carb and Crossfire. In your case you'd have to remove the 86 dash harness Lamp Driver from the CHECK ENGINE circuit. This thing is a huge PITA to access,.... better off cutting it's wiring and bypassing it rather than trying to actually remove it from the dash harness !



Can an 86 Carb dash harness be used for a 87 fuel injected engine,... YUP. ( My 84 has an LT1 in it.) But it will require a lot of modifications/additions for things that a carb car isn't equipped with. It might cost more $$ to buy the correct/matching TPI dash harness, but doing so will resolve a LOT of compatibility conflicts that will have to be addressed for a successful conversion.

 

thank you for the help. now I have to figure out what to do. I have a 88 fb dash from a tpi formula, a 87 dash harness from a 87 iroc. and a lb8 dash harness out of a 85camaro. all my othere parts cars are 91 and 92 years

 

The one you'll HAVE to use will need to come from a Firebird.

You didn't mention if the 87 LB9 harness was from a Camaro or Firebird,....... It SHOULD be used from a Firebird because of pop-up headlight wiring and electric speedo wiring. If your car has a 700R4 than you should use an automatic harness ! ( if the car is a stick than it shouldn't matter - much ! )

The best matching Firebird dash harness for an 87 LB9 Firebird ENGINE harness will be from an 86-87 Firebird TPI. The next best dash harness would probably be from a 86-87 MPFI ( 86-87 just because it has PPD wiring). An 85 Firebird TPI Dash harness next, then a 85 Firebird MPFI, than an 88 Firebird TPI, then and 88 Firebird MPFI,... and so on. They can all be made to work, it's just getting too the best starting place possible. ( you know ----------> $$ spent vs. time and effort ) `

The best matching harness on your list is from the 88 Firebird,..... But there WILL still be some mods you'd have to make. The 82-87 dash harness ends at the drivers side kick panel where it connects to a 'body' harness, then that 'body' harness connects to the tail light harness. The 88 is different,.. the 88 dash harness runs past the rocker panel and connects directly to the tail light harness. If you compare the spare 88 Firebird dash harness to the dash harness in the 86 you will quickly see what I'm trying to describe. You can overcome this problem with a lot of cutting/splicing or by installing an 88-92(?) tail light harness along with the 88 dash harness. ( keep in mind a 'regular' Firebird / Formula tail light harness is different than the Trans AM/GTA tail light harness. )

* In 88 the Wiper Wiring moved on the C100 firewall connector and a different wiper motor assembly was used..... if you use the 88 dash harness with an 87 ENGINE harness you will have to resolve this conflict.

I hope this helps in some way !

 

yes sir.!!! Sounds like a 86 or 87 firebird roller that has engine and dash wiring still in it is what I need to look for. I thought the headlightswere in a seperate harness that goes through the firewall by the brake booster

 

Yup,.. Your right - I'm wrong - about that Headlight harness. ( Time to stop working from memory I think ! )

I thought there was 'extra' Firebird headlight stuff on C100 - and they is - but not on the ENGINE side of the 2 engine bay C100 plugs. ( They ARE on the HEADLIGHT harness side; A1, D1 & D2. ) After seeing that I think the only difference in the ENGINE harness (for the same year) from Camaro to Firebird is that the Firebird ENGINE harness has the electric Speedo wiring on D4 & E4; that seems true for the 87 anyway.

This is the 87 Firebird C100 schematic:

 

thank you again! So 87 birds all came with no mechanical cable speedo? I have an 84 that does. wonder what the last year for them was. Any chance I could put older cluster in and run the cable? Oh.Buy the way. I have 2 harnesses both 87 types. one from a ta and one in an iroc. So that takes me back to the dash harness that has no elec. fuel pump. Buy a complete 86 fb 3 hrs 1 way and 1k. or just a dash harness for 277.00 I havnt brought the car home yet. so I dont know what that has cluster wise. thanx again

 

Correct,.. all 87's Firebirds will be electric Speedo.

Firebird Speedo change was in 86,... in 86 the V-6 cars WITHOUT gauges got a mechanical speedo, but I believe ALL others were electric that year. So; If you want a full set of gauges and a mechanical speedo than your looking at 85 and earlier clusters.

The only way to answer the question " Any chance I could put older cluster in and run the cable?" would be to have the plug diagrams for the electric speedo and the mechanical speedo to compare the clusters to see what is - and what is not - going to match up at the cluster plugs. I will say this; I converted an Firebird 86 non-gauges cluster ( -factory MPFI) to a full gauge cluster (+ Factory LG4) and IIRC the only things I had to modify was the ECM "CHECK ENGINE" circuit and I had to add a VSS buffer. I don't think I HAD to add the VSS wiring to the dash harness - but that was at least 15 years ago so do your homework to BE SURE ! (* I don't have any 85 or earlier Firebird schematics....... I've got some most 86-thru 88 schematics.)

For what it's worth; I've got a few dash harnesses available. 1 from an 86 Firebird TPI Dash Harness (Electric Speedo) and *I THINK* I also have an 85 Firebird TPI harness (Cable Speedo). The 86 harness is boxed-up and the 85 (I think) harness is still connected to a dash housing. I haven't pulled that stuff out for verification,.. but I'm fairly certain I've got those 2. I know I've got one from an 84 but 82-84 will be carb. I might have 1 or 2 others,.. but not sure what those might be. (Most likely 86-88 to).

 

I went and picked up the 86 firebird today and got it home. After unloading it I had my first chance to look it over for mor than a few min, I noticed a few things that weren't right for an lg4. like fuel lines on driver side and the words fuel injection on door handles. I washed the sap off so I didn't see it the day I went and checked it out. vin says it's a v6 car also' 8th digit is an S. I will look closer at the gauges tomarrow. . I think the 700r4 I have has a electric speedo gear. If i'm not mistaken the v8 have different pulse count than v6.. I will do a search and see what I will need to do. Putting the 87 ta engine harness in should be a little better now.