Wiring my drag car

Ive stripped everything from my car.

I put an Lt1 into it
original wiring harness.
engine is mechanically solid, ran strong when i pulled it

attempting to wire it into my car
It wont start.

Ive created a page of the wiring i have done
www.geocities.com/coolhandz69/LT1_Wiring_guide.doc
Some part of the wiring must be wrong but i cant figure it out
please look at the above list and give any suggestions
(might need to cut and past link, may not work directly.)

extra info:
AIR/EGR disable
Vats programmed out
OBD1 computer (96 engine and harness)
fuel pump runs
no spark or injector pulse
computer is not sending the "ignition control signal" to the ign cont module
coil and injectors have power
maintains proper voltage (9.6V) when cranking

Check your opti and harness. No signal from the opti=no spark and no fuel. Have you checked for any trouble codes?

the opti and harness are good

Not sure how you determined "good", but I would electrically check every wire from the opti to the pcm and from the pcm to the ICM. I would also look at all the pins/connectors on the pcm, to be sure they are making contact and nothing bent/broken.

What about codes? If you are getting DTC 16, your engine will not start and you will get no SES.

My first reaction was exactly the same as Rob's....

How long does the fuel pump run"

You really need to "scan".

I notice your wiring guide is for the 4L60E. Have you taken care of all the stuff like the neutral safety switch? Since you created the document, I'm assuming you are in fact doing a 4L60E install, and this isn't something like an issue with the clutch switch on the manual tranny version.

no, i have only done the wiring in the spreadsheet. What needs to be done for the 4L60-E hookup. I thought it was all self contained in the engine wiring harness.

after a second thought, i have not done anything with the neutral safety switch. how should i wire that? would grounding wire C230-J (orange/black) fix that problem. that is circuit C3-15 from the computer.

Originally posted by coolhandz
no, i have only done the wiring in the spreadsheet. What needs to be done for the 4L60-E hookup. I thought it was all self contained in the engine wiring harness.

after a second thought, i have not done anything with the neutral safety switch. how should i wire that? would grounding wire C230-J (orange/black) fix that problem. that is circuit C3-15 from the computer.

Grounding "J" would satisfy the pcm to tell it is in either park or neutral, but you might not want to do that. The pcm uses different engine control tables based on that input.

There are all kinds of different wiring diagrams on my website that may assist you.

Originally posted by shoebox
Grounding "J" would satisfy the pcm to tell it is in either park or neutral, but you might not want to do that. The pcm uses different engine control tables based on that input.

How so, in the wiring diagram it shows this circuit going from the computer to the switch to ground. the schematic of the switch shows it as grounded when in park or neutral. i dont see what multitude of signals are possible besides open circuit, or closed circuit. is there more to this switch that i dont see?

Originally posted by coolhandz
How so, in the wiring diagram it shows this circuit going from the computer to the switch to ground. the schematic of the switch shows it as grounded when in park or neutral. i dont see what multitude of signals are possible besides open circuit, or closed circuit. is there more to this switch that i dont see?

Yes, it is either grounded or open. The pcm senses park or neutral when grounded. What I meant was, based on that, the pcm will use, for example, a different table for idle speed when in park/neutral than when not.

oh sweet thanx. that makes sense. I'll ground if for now to get it started. once i get my shifter installed, I'll properly hook it up.

thanx again

hey cool handz, your spread shows the fuel pump prime as switched?

Do you have the fuel pump running to a relay? I ran mine off the green wire from the pcm, then let the relay handle the current going to the fuel pump.

Do you have the MAF attached to the intake? My truck would run for about a second, then die cause it wasn't getting a maf signal. have you grounded the pcm? made sure all the powers were right?

I have been through the wiring harness in detail and can hopefully help ya out, let alone Rob (shoebox), he helped me out a couple of times when I was stumped.

I ran a B&M ratchet action shifter and used the switches that came w/ the shifter to let the pcm know when I was in gear and when I wasn't. Works fine hooked up or not, it's up to you.

BUT if you are running an alternator, watch out! You have to tie the return to a resistor to limit the current going back to the voltage regulator (wire in harness that plugs into the alt.). I burned through 4 alternators before figuring that out.

Definitaley check out Rob's site, get the PCM pinout, you can easily find all the powers and grounds through there, and make sure everything is wired up.

Oh, the torque converter circuit, should be switched, then when you hit the brake, it opens the circuit, it actually powers the tcc, then when you hit the brake, it pulls the power and shuts the clutches down. I used a relay for that as well, you can get them from autozone or advance for $3.99 a piece, cheapest I have found around town.

Good luck.

Originally posted by Hotwire
...

BUT if you are running an alternator, watch out! You have to tie the return to a resistor to limit the current going back to the voltage regulator (wire in harness that plugs into the alt.). I burned through 4 alternators before figuring that out.

...

...and that's why they call him "Hotwire" ! :lol:

Glad you offered help. It's good to get help from people that have already been down that road. :bow:

yeah i dont think that having the fuel pump prime hooked up does anything. I have a fuel pump controller (aeromotive A1000 billet FP controller) that gets turned on by the relay wire, powered seperately, and regulates by the tach signal.

MAF is good

Im hooking the PNP switch up next and crossing my fingers. I just have to wait until i can go home from school to try it. 500 miles isnt a regular weekend trip ya know.

i actually have the newer model brake switch, im gonna mate that into my system to run the torque convertor lockup and the brake lights.

now about this alternator thing. can you please explain better. I have the alternator just hooked up regular. I thought there was a simple conversion you could do to your older GM vehicle's harness to use an internally regulated alternator. i think all you have to do is remove the external regulator and splice two of the wires, or something like that.

Honestly, the PNP signal has nothing to do w/ your truck not running. I had mine disconnected for the first month I had mine on the road.

The regulator on the alternator needs a feedback wire to determine whether to charge or not. When I first wired mine up, I threw it straight to +12v, not only did I have a current drain killing my battery, I was popping the regulators after the truck ran for about 5 minutes and tached up a little.

Another person on s-seriesforum.com did the same thing and told me about it.

If you look rrrreeeeaaaallllly close at the schematics for the alternator wire, it runs all the way up into the dash board, to the cluster, then it goes through a 470 ohm resistor, and gets tied to the ignition switch. The resistor keeps too much current from going back through the regulator and killing it. I think most of the time, they just run it through the alternator light bulb which provides the resitance it needs, but not positive about that, thats why I ran resistors.

I ended up doing the ohms law formula and going w/ two 1/2 watt resistors, 1K (1000) ohms in parallel to make up 500 ohms. I just cut the wire coming off the alternator, soldered them in, put heat shrink around them and forgot about it. Runs like a champ now, hooked it up to a switched source too.

Maybe the pcm is sending the signal but the Ignition module is fried.. have you try with another module ? my car die once because of this little thing.. :irk:

good look :thumb:

nope not sending the signal. I measured with amultimeter and labscope.

well i still cannot get it started. I cant count how many hours i have spent reading my service manual and fiddling with the wiring. I really have to get it running. I moved out four years ago and my car is still in my dads garage. he said that his car aint sitting outside another winter and hes gonna make me sell it if i dont get it out of there soon. i think im gonna have to just buy a conversion harness. I dont know what to do.

i tried messing with the PNP switch. that didnt help. i have gone through every step of the tech manuals troubleshooting to check the functionality of the distributo wiring and it all checks out. you guys have any more ideas? anybody live close to Toledo and wanna make some money coming down here and getting it running?

ok, using a 96 harness and a obdi pcm is out of my range, I don't know the wiring on the 96, so everything I am going by is from my 94 manuals for the obdi pcm. you may need to ohm the wires out to make sure they are going to the right pins on the ecm.

c220

E as pcm ign, in my 94 (OBDI) manual that lists as the throttle position sensor signal to the brake control, if that's how you wired it up, you may be sending +12 V through your tps, or pcm, and may have screwed something up.

F - tan wire is the serial data signal that goes to your ALDL

C230

G- pnk- should be a switched power feed

H - tcc power, should have switched power running through relay for tcc to lock up, when brakes applied, relay breaks connection and kills the power to the tcc releasing the clutch.

K - tan/blk - torque converter clutch control - don't think I did anything with that, can't remember

C100

F - brn - switched power feed

K - pnk - should be a switched power feed

C105

My manual doesn't list a C105

Good luck man, hope you find it. I'd pull the PCM connectors, just apply power and probe the pins to make sure you have power and ground where it's needed, then branch out from there.

Or do you have a obdi conversion chart from somewhere?

no, i dont have a chart i was trying to create one. It lloks like form our two wiring diagrams that the harnesses are much different. i pulled all of my data straight from the service manual, and yours are much different. So im sure that its a difference between the two years. my problem still is that i have to get mine to work. I dont see anything else that must get hooked up for mine to work

Anybody have any ideas how i can check codes on my computer. I dont have the MIL hooked up, i have an OBD2 data link and an OBD1 computer. I have the connectors to hook up the diagnostic link to my computer but i cant find any freeware that will allow me to check data trouble codes. anybody know of any?