BahN

Hey guys, got my LT1 in the car. Just finished up my wiring. And heres where the troubles begin.

I'm able to connect, read, and program my ECM. So the ecms getting the correct power (both constant, and on ignition). The car wont start. So i decided to check RPM on my datalogger to see if the opti was telling the ecm the motor was spinning. Even with the key in the on position (not cranking) it shows 50 RPM, while cranking it stays the same. 50 RPM, dosnt move. I've checked my wires to the opti and made sure they are right. I know on some models its easy to put the opti connector in backwards, but mines in right.

Any ideas? =/

Klortho

Make sure you have power to the coil, the C100 connector in the LT1 harness has the wires in it, also make sure you are getting power to the injectors, there are two pink wires in the C100 LT1 connector has those wires also. (I actually found my old wiring diagrams from when I wired mine up)

BahN

i checked all wiring and its fine. However i did notice that the ECM is grounding out all the injectors (they already have ignition power via the pink wires) so they are always on. I disconnected every ECM cable except the red and retested. Same thing. So then i checked every pin on the red connector for a ground, only one, pin 2 which is suppose to be a PCM ground, so thats fine. I then probbed the ECM pins itself via an ohm meter. Over half of the pins have very little to no resistance with the ECM ground, including all the injectors.

Pretty sure its a bad ECM unless anyone can shed some light?

Firebat

iTrader: (7)

I wouldn't suspect the pcm right away. If its reading, scanning, and able to program then its probably good.

Got fuel pressure? Fuel pump on, hear the fuel pump when turning on the key? I think there is a theft det relay that can cause the car not to start if you don't wire it out, even with vats programmed out.

Could also test the coil: http://shbox.com/1/coil_testing.jpg

Could also test if signals are getting to the opti: http://shbox.com/1/4th_gen_tech2.html#opti_test

BahN

just got back from a junkyard, their LT1 ecms do the same thing mine does, so i agree, not the ecm. I have already programmed and wired out VATS, i have fuel pressure and my pump is brand new and running. I haven't tested the opti yet, i will go do that now and get back to you.

BahN

k, did some testing, i have no power on pins A or D on the ICM harness. The coil is brandnew, so is the plug wires. Below is a picture i made with my results with the ignition in the On position.

Are these correct? I cant find pinouts for the opti harness anywhere.

Firebat

iTrader: (7)

I'm going off of this:


ICM connector unplugged - You shouldn't have 12V on pin C of ICM. Its shown as going to ground, your ground is probably not connnected. C should equal 0V and also measure 0 ohms to ground for resistance. A should be +12V with the key on. D and B - wouldn't worry so much about voltage, you should measure resistance across D and A and it should be the same resistance as the coil, with the ignition key off of course.

Firebat

iTrader: (7)

http://shbox.com/1/4th_gen_tech2.html#1995_pcm_pinouts

Opti connector- looking at the pic on my previous post,
D=B3
C=B14
B=B20
A=B2



*Note: these diagrams are for a 95 camaro/firebird LT1, if you have a different model car or year, it may vary slightly, or may not

BahN

thanks for the replys, ill go out and check everything and get back to you!

Klortho

Here's one of the main ones you want to check and make sure of, there are more than one grounds going to the PCM as shown below.

Klortho

Also, don't forget there are two power wires that goto the PCM, a pink switched and an orange constant.

BahN

K, i checked my icm wiring is different from the diagrams? I drew a picture below. Also my opti wiring checks out fine. i have 0 resistance between A and D. I don't think my opti is telling my ecm its turning. Because i have no injectors firing. Also is there a wire that goes from the ECM to the starter solenoid to tell it it's cranking? or does the opti do that?

Edit: Saw your new posts, My ecm is getting the correct 12v constant and 12v on ignition. Also, my ecm has 3 grounds they go to the ICM bolt in the head. The block is grounded via a intake to firewall ground, and a battery to passenger side head bolt ground. I have confirmed the ground is working.

Also, i'm not using the fuel pump relay at all. I have my fuel pump on an ignition source. Shouldn't be an issue should it?

Klortho

Should be a big ground coming off of the coil as well that goes to the driver side frame rail, without that on there that may be your problem....let me go out and take a picture of it and I'll post it up.

BahN

thanks so much man, i really appreciate you trying to help me out here. I'm dieing to get this motor started. I hooked up my tuner and was able to pull some DTC's. Its throwing 36 and 41:

36 Distributor ignition system (faulty high resolution pulse or extra low resolution pulse detected)

41 Ignition Control (IC) circuit (open circuit)

Klortho

Here's the pic, sorry about the quality...crappy cell phone.

blah, it doesn't look right, I'll have to wait until my digital camera gets home, but basically it's a large amount of wires that goes to the coil in a bundle and has a grounding strap that goes to the driver side frame rail

BahN

ok, is it one of those braided grounds?

Klortho

Yes, goes on a lug on the coil bracket to the head, also has a set of grounds on it also.

BahN

Ok, i have the ones circled in red in this picture. None of them go to the frame rail though. Also whats this in the blue circle? on mine it goes directly on top of the coil itself??

BahN

checked connections and reset codes. No more 36 or 41, but its still not firing. I tryed 4 different times after clearing the codes. However non of the other codes like coolant sensor came on like they did before. How long does it take to throw a code??

Klortho

What is circled in blue is not right, those connectors hook up to the coil itself.

Klortho

I bet these are going to be huge, but here are some pics of mine, I couldn't get the MAF out of the way, but I think I got some of the connectors on the coil as well.

Klortho

a few more

Klortho

Found this also, may help out as well (it is a '93, but the layout is the same)

BahN

thanks, ill run a ground tomorrow or later tonight and check. Do you know if their is a diff between the 96-97 ICM and the 94-95? I'm running a 94-95 coil with an 96-97 ICM, i just noticed the part #'s are different.

chevyowner02

iTrader: (3)

I know the coils are diffirent so I would say the ICM is also.

BahN

think that could be my problem?

chevyowner02

iTrader: (3)

Could be I know you can run the 96-97 coil off the 94-95 ICM but I don't know if you can run it the other way.

BahN

ok, update. Changed ICM to a 94-95 model. Same thing. Tuner dosnt see any revs. Just shows 50 at all times even when not cranking. I read somewhere else that the ecm shows 50 rpm at all times even when not cranking, is this true? If so, could it be that might starter/battery are not cranking the motor fast enough? It does sound a little weak, but i think it's hitting 70-80 at least.

Also, after checking all my wiring, i'm pretty sure it's not the issue. Only one thing left, the opti.

Any last ditch ideas before I pull it?

chevyowner02

iTrader: (3)

Yea you can try this befor you pull it http://www.camaroz28.com/forums/showthread.php?t=601565

BahN

problem narrowed down to the battery. If i keep the ignition on and unplug the coil from the opti. I can manually spin the crank and you hear the injectors fire, and see spark via a plug. When i crank with the starter i don't see spark. And it cranks slow. So my battery doesn't have enough amps to push it through apparently.

BahN

Problem found! But no solved.

The line i choose for 12v when ignition is on has NO voltage while the engine is cranking. Where's a good line to steal this power from for a 87 that use to be an LG4 CCCarb?

Klortho

Pretty much any pink wire, that will be a switched 12v source, just test it a couple of times to see if it turns on and off with the key.

BahN

IT LIVES!!!!!

Klortho

WOOT....awesome, it always is a good feeling when it fires up for the first time.