so im tryin to finish up my wiring and havin a couple issues gettin the truck harness to go with my cars stuff. mostly at the C100 plug.

so i sold the harness and ecu from the car but got another c100 plug from the junk yard. some of the pins are in different places then my factory onesbut its alright cause i can repin. the issue im havin is goin off the pinouts from a 1992 c100 pinout they dont seem to match up with my 91's c100 plug.

heres a pic of what i mean.

 

also since i removed my factory ecu how would i wire up the starter? im not getting any signal to it. i can get it to turn over by jumping to any ignition source but not through the purple wire itself.

 

Well the starter issue I can touch on. If you dont have C100 done, you wont have any power feed to the ignition switch for the PPL starter lead. There should be two large gauge red wires coming from the battery to supply voltage to the fuse box which feeds everything else. The PPL wire gets it supply from one of those two leads via the starter switch.

If you have all of that done, you need to make sure your shifter wiring is setup correctly since that acts as your nuteral safety switch. I believe the colors are PPL (goes to the starter) and YEL (comes from teh starter switch) at the shifter harness. Both will be heavy gauge. They must be connected for the PPL wire to get voltage to the starter.

Things may be different for your 91, I am not sure since my 83 dosent have VATS. But that is how my system works.

 

alright so your sayin that if i connect the PPL wire and YEL wire together it might turn over? i got one of those stupid mega shifters and the PO just left the original shifter plate thing under the console. maybe i can get a pic today.

 

Yes, if you connect those two wires and everything else is hooked up correctly, it should turn over. Make sure if you jumper them to use the same gauge wire.

Just remember if you bypass the shifter switch, you will have to make sure it is not in gear before cranking. With an auto tranny the engine will start up and then the car will move once the tranny develops enough pressure.

 

well tried jumping them and didnt get anything. i dont even have any power goin to those wires.

jumped the purple and the tan/white

 

i think thats because you have no power going into the c100 from the battery. i'm pretty sure a4 and g5 are going to need fused power off the battery, then the interior should be powered and your purple starter wire should get power.

 

nope the power was goin into the interior. gauges and stereo turned on.

 

goin to follow this diagram and see what happens.

 

I went and read a schematic for a 91 Z28 and that TAN/WHT wire (pin A) comes from your START ENABLE RELAY. There should be a BLK/YEL wire shown as pin B, if you ground that wire the VATS starter disable system will be effectivly bypassed and you should get 12v on the TAN/WHT wire during cranking.

Connect the TAN/WHT wire to the PPL wire and the car should turn over.

I dont know if VATS shuts down anything else, but I am pretty sure it disable the ignition or fuel as well, so I dont know if that would affect your conversion or not depending on what fuses you used to control your LSX computer.

 

alright so ground the BLK/YEL wire on the starter relay, jump the PPL and TAN/WHT wires and it should probably fire?

 

Check to see if you have 12 volts on the YEL wire during cranking. If so, ground the BLK/YEL wire and yes it should turn over.

Starting is something different. I dont know who or how your harness was done so I dont know if it will actually fire. According to the schematics the grounding of the BLK/YEL wire should get the starter working.

 

alright just grounded the yel/blk wire and jumped the ppl and tan/wht and it cranked. awesome. one more step out of the way.

thanks alot.

 

Glad it worked for you.

 

now i just gotta figure out my C100 plug issues.

 

almost done with my swap just need to wire the plug for my alternator. when i bought the harness off the guy he clipped the plug for is carb setup. i got a plug and pigtail from the junk yard. my harness is a 2001 silverado 5.3l and i got a grey and a brown wire goin to the alternator, the plug i got has a red and an orange. does anone one know what goes where?

thanx in advance

heres from the harness:


heres the plug i got from the junk yard:

 

Alt pin B to R15 (red or brn), pin C to R52(gry)

 

ok next thing im havin an issue with. my buddy is coming to sorta tune my car today and need this workin

i tried wiring up my OBD2 connector today and scan it with my little scanner and it wont link. i checked and rechecked the wiring and everythign is goin to the right places. anyone have a clue on whats wrong?

im goin off of this diagram:


and this is my harness (i have B58 goin to #2 port)
http://www.lt1swap.com/99-02_vortec_pcm.htm

 

nevermind it ended up working.