Originally Posted by crainholio

The data below is my latest summary on the project progress.

PCM wiring needing connectivity with the car's chassis harnesses:

CKT_NO DESCRIPTION
340 Battery 12VDC to PCM
48 Clutch PP Switch
335 Fan 1 Relay Control
340 Battery 12VDC to PCM (tied to above ckt 340)
451 PCM ground
439 Ignition-switched 12VDC to PCM

465 Fuel Pump Relay Control
121 Tach Output
473 Fan 2 Relay Control
428 Evap Cannister Purge Solenoid (can wait)
1310 Evap Cannister Vent Control (can wait)
817 VSS Output to Speedometer
419 Malfunction Indicator Lamp

Independent of the PCM, I need to bring ignition-switched 12VDC from the interior fuse panel for the injector harnesses (INJ 1, INJ 2 fuses), as well as ignition-switched 12VDC for the {fan 1, fan 2, fuel pump} relay pulls. No under-hood fuse panel on 3rd gens, they're all under-dash.

I'll need to fabricate a 12VDC fused feed from batt positive to the fan relays to feed the fan motor relays, and another 12VDC feed to the fuel pump relay.

Electrically, this looks like it for now. I'll need to come back to the ALDL/OBD-2 connector, and the gauge {oil pressure, coolant temp} feeds instead of using the Class-2 Serial Bus which outputs in unuseable form for my gauges. Plenty of unused wires in the thru-fender LS1 harness I can repurpose for those, and land them right in place to connect to the 3rd gen chassis C207 connector in the pax
footwell. The remainder of the wires hit the 3rd gen chassis C100 connector on the driver side firewall.

Originally Posted by MrDude_1

heres some bits from some PMs i had with a friend on another board:

************************************************** ******

what year LS1 is it? i only know the 99-02 wiring, not the 98 wiring (the freak year.. lol)

these are all the connector pinouts: http://66.83.134.202/travis/LS1swap/...connectors.txt

let me take a min to explain what that means (i know i wish someone did that for me first.. lol)

when you get a pullout that has the harness on the car, everything is connected except:

3 connectors that were underhood. (named C100,C101,C105)
2 connectors that used to connect under the dash (220,230)


so these 5 connectors are teh ONLY wires we're worred about.

in a nutshell... give ignition power to the pink wires, constant power to the orange ones, take off VATS, and it runs.

the other wires you hook up are just gauge wires, reverse lights, ect.... nothing hard.

its ALMOST a stand alone harness already... only diff is it will have a couple extra wires left after its hooked up.. not a big deal..

also, i bought HPtuners... you will either need HPtuners, or have your PCM flashed to remove the trouble codes and VATS.... if you buy HPtuners, this is NOT hard to do.. i could give you a step by step on doing it easily.... but HPtuners is a little pricy. a tune is a cheaper route, but HPtuners gives you the scanner thats very useful.. along with the ability to change stuff at will... your call on that.

*********************
biggest tip i can tell ya on buying one:
avoid 98 Fbod engines and corvette motors. the 'vette motor is WORSE for ya since it requires switching almost everything "vette specific" to fbod specs... the 98 was a oddball year with a diffrent wiring harness (less support and help online) and a PCM that just isnt as good.... 99+ fbody engines only.

VATS works like this on 3rd gens:
you put the key with the "chip" in.
the "chip" is just a resistor. but it has to be the right one.

when the correct resistor is in:
the VATS module on your thirdgen does two things.

enables the starter relay.. this allows the engine to turn over

sends a signal to the ECM.. this signal is a constant pulse at a specific frequency. without this pulse, the ECM will not fire the injectors.

when the wrong resistor (or no resistor is in):

security light comes on

car will not start for 4 mins, even if the correct key is in there (to prevent someone from just going thru all the combos fast).... everytime its retried in that 4 min peroid, 4 MORE mins are added, upto the max time. i dont recall what the max time is.

biggest tip i can tell ya on buying one:
avoid 98 Fbod engines and corvette motors. the 'vette motor is WORSE for ya since it requires switching almost everything "vette specific" to fbod specs... the 98 was a oddball year with a diffrent wiring harness (less support and help online) and a PCM that just isnt as good.... 99+ fbody engines only.

VATS works like this on 3rd gens:
you put the key with the "chip" in.
the "chip" is just a resistor. but it has to be the right one.

when the correct resistor is in:
the VATS module on your thirdgen does two things.

1. enables the starter relay.. this allows the engine to turn over
2. sends a signal to the ECM.. this signal is a constant pulse at a specific frequency. without this pulse, the ECM will not fire the injectors.

when the wrong resistor (or no resistor is in):

1. security light comes on
2. car will not start for 4 mins, even if the correct key is in there (to prevent someone from just going thru all the combos fast).... everytime its retried in that 4 min peroid, 4 MORE mins are added, upto the max time. i dont recall what the max time is.

**********************

VATS works like this on 4th gens:
you put the key with the "chip" in.
the "chip" is just a resistor... but it has to be the right one.

when the correct resistor is in:

the Body control module (BCM) on the 4thgen does two things.

1. enables the starter relay.. this allows the engine to turn over
2. sends a signal to the PCM.. this signal is either a pulse like the 3rdgens, but at a diffrent frequency.... OR in the case of the late late LS1s, its a serial commucation thing where the BCM talks to the PCM saying all is well.... without this, it does not fire the injectors, and it does not spark the coils.

when the wrong resistor (or no resistor is in):

1. security light comes on
2. car will not start for 4 mins, even if the correct key is in there (to prevent someone from just going thru all the combos fast).... everytime its retried in that 4 min peroid, 4 MORE mins are added, upto the max time. i dont recall what the max time is.

so heres what i did.

1. i left the stock VATS 3rdgen system ALONE..... someone tried to steal my car once... VATS was the ONLY thing that saved it.
2. in HPtuners, the VATS can be turned off in the fbody PCM by clicking a checkbox... REALLY REALLY EASY... with this box checked, the car will run. it will set DTCs (trouble codes) because parts are missing (like rear O2s, AIR, EGR, fuel tank pressure, coolent level sensor, ect.. because stuff isnt there basicly, but with HPtuners, thoes are easy to fix. just more clicking.) but the car runs.
   
   hereswhat you COULD do... on ebay theres a box like the tach adapter box. this box sends the proper signal to the PCM... wire it in (ignition power, ground, PCM signal) and its set... but you need to flash the PCM anyway for the DTCs... so you might as well skip that and either have your tuner take it out, or do it yourself in HPtuners. (another $50 in lesson saved.. lol)
   
3. the 3rdgen VATS to PCM wire goes nowhere...... if you're wondering why leave it..... the starter disable. without the proper VATS key, it still wont crank over.

for EVERY wiring diagram on a 91 Fbody go here: http://66.83.134.202/travis/91FbodyWiring/

i also have some 92 Fbody diagrams someone emailed me, but i know nothing about them.. the 91 ones are almost all exactly the same as the 92s... where the slight diffs are should not matter with this swap.

btw, save everything i link to your hard drive.... my server may not be up forever.

Originally Posted by robsm88

What is the small coolant line from the radiator to the throttle bady do besides warm the intake air temp? Can I just bypass the throttlebody?