djlunchbox

this is driving me nuts guys, please chime in if you have any ideas. i'm at a loss.

i have a 95 LT1 no start condition. i followed the steps from shoebox to try and fix it.

i have good fuel pressure. (bout 50 psi @ the rail)
no spark at the plugs
no spark at the coil
no injector pulse
i have the correct 12v,5v,5v, ground at the opti connector.
i see no corrosion at the opti connector but cleaned the contacts just in case
brand new GMPP opti from summit installed a few hours ago. still no pulse
i am using a noid light, and i tested the light to make sure.

i forgot to test for 12v at the pink wire on the injectors, i will do that tomorrow.

what else can i check? its super cold out and i need to get this motor running.

a little fyi, i havent tried starting it in months, last week i turned it over after fixing some other things and it started and ran strong. i turned it off and tried starting it a few minutes later and nothing. no spark, no pulse. what the hell is going on here. all my checks seem to point to the opti, but this one is brand new from summit ( advertised as brand new ac delco gmpp)
my local gm dealer is well over 600.00 for a new one.

what am i missing?

Injuneer

Have you scanned it for codes?

djlunchbox

hey in, glad you replied. no, i have not. i am using a street and performance harness, and it has never worked right since i put it in. i have a auto xray that came with the motor when i bought it, used to work with the old harness, with this new one, nothing. so if you had to trouble shoot this without a scanner, what would you do. keep in mind, this is not in a F-body. this is a custom install in my GMC truck.

djlunchbox

any ideas?

95TA04GOAT

Sounds like the opti isn't producing the high or low resolution signal, the computer isn't receiving it, or the computer doesn't know what to do with it. So, opti, wiring or computer seem like the most obvious culprits. I'd double check the wiring considering it's a custom install with an aftermarket harness.

djlunchbox

according to the tests i've seen on various sites, my wiring is good. all my voltage is correct where it should be. grounds are good. i will have to try and get data from the computer. damn this s&p harness. i've had more problems then good from it.

4THGEN Z

does the ICM check out OK?

Injuneer

Have you tried connecting the output of pin D30 (serial data) directly to the correct pin in the scanner?

95mysticta

have the same problem with mine i wasnt getting any injector pusle or spark. both the coil and module were in good shape turned out to be the opti. found alot of corrosion on the optical sensor and hence why it was toast and wasnt getting any spark or injector pulse.

thats just how my scenario turned out... got a new opti and all new seals for the front of the engine and should be back and up and running smooth later today.

Injuneer

That's the advantage of a scan.... it will show the codes for faulty/missing pulse signals from the Opti optical sensor (DTC 16 for low res, DTC 36 for high res). Another check would be put a digital volt meter on the signal wire for the low res pulse (black wire to ground), and slowly rotate the Opti, looking for the voltage to switch between 0v and 5v as the slots pass the optical emitter/receptor.

djlunchbox

yes, voltages were correct as of a few weeks ago. i can retest it for my piece of mind tho, i don't remember how to do it now. i should have it written down somewhere.

djlunchbox

no i haven't. i should just need to do that and i assume a ground on the other pin? i'll have to look at my scanner this weekend and check on that first. i would love more then anything to be able to use that. life would be so much easier.
i will also check the opti like you suggested injuneer, with the VOM. i am jsut a tad confused on which wire to probe. when you said "black wire to ground" i am assuming you mean on the meter, not "probe the black wire on the opti harness". when i was testing for voltage going into the opti, i got 5v on both my low and high signal wires. the low res wire that you want me to check, does that pulse?

tell me if this sounds ok.


pull opti back off the motor
hook the connector back into the opti
KOEO
black probe of meter to batt ground
red probe of meter to low res wire connected to opti
pin opti slow and see if volts bounce from 5v to ov.

won't the meter just read a consistant 5v?
forgive my noobishness



happy thanksgiving all, hope you're all stuffed!

Injuneer

Yes, black wire on the multi-meter to ground. Use the pink/black wire in the Opti harness for the ground. Red wire on the multi meter to the red/black wire in the harness.

Look at the PCM pinout lists on Shoebox's site. For pin B2, the voltage is shown as either 0 or 5 with key on, engine not running (depending on whether there is a slot or a solid part of the wheel in the optical sensor). With the engine running, the pinout shows "varies" for the voltage. Since the output of the sensor when it is operating is switching back and forth from 0V to 5V the voltage measured with a DC meter is going to be in between.

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

As far as what is connected to the ALDL connector, again refer to Shoebox's ALDL pinouts:

http://shbox.com/1/dlc2.jpg

Look at pcm1 on the 95 wiring diagram for where to pick up those points on the PCM (not all of them come from the PCM). Although the diagrams are for a 95 with the 16-pin connector, you are looking at where the source for B+, ground, serial data is, not which pins they connect to. You have to match your cable or scanner connector to the 12-pin layout.

djlunchbox

excellant, thanks for the info! i have used the first link, but the second link i have never seen before. i wonder how i missed it on shoebox's site???? either way, i will test it all tomorrow and get back to you, hopefully i can get this fixed soon. it will be snowing soon and i have to work on this in a portable garage.

djlunchbox

ok, an update for ya.

i just got back from working on it a little more.
the new opti checks out ok. i tested it per your instructions injuneer, and it is all good. so is the old one . grrrrrr.... at least at low rpms it is anyhow.
so i moved up the harness to the passenger side valve cover connector and checked it there. all is good. as i turned the opti by hand , the fuel pump would come on and off, and i would hear a "click" sound. i was curious to see if it was the injectors clicking, and i couldn't tell by touch, so i unplugged them all. the clicking stopped. i tested a few different injector connectors with the noid light as i turned the opti, nothing. i checked all my fuses at the harness fuse center (remember, aftermarket) all were good. (there is only 4). i am stumped again. so then i notice that the ICM connector i unplugged, so i plug it in and turn the opti by hand again. nice blue spark arcs from the coil wire connector to the body of the coil (ground.) so i say holy ****, and put the wire back on, and test the opti for spark. it passes spark to all the plug ports, so that is good. STILL NO INJECTOR PULSE.... stumped again.
i take a break from the opti drama, and move into the truck to troubleshoot the data connector not working. here is a pic of how i had them make the harness for me. sorry its blurry, couldn't get the camera to focus right. it's the back side of the connector, and there is 3 wires mounted in the right spots ( according to the diagram that was linked above)




i decide to check for continuntybetween the tan wire on my connector and pin D30 at the PCM. i have it. just for giggles, i check for continuity on the ground wire at the connector, and pin D30. i had it there too!. i think, "that doesn't seem right...." so i check the other wire that was there, white wire, and it too tones back to the other two. so i check from D30 at the PCM to the floor of the cab, BAM, it tones for me.... (multimeter continuity tone) .
i remember that when i was removing the dash, i saw a splice that was shrinkwrapped over. so i cut the shrinkwrap away and look what i find:



over 5 years have passed with me not having a PCM connection because of that.
needless to say. i will never purchase another harness from streetandperformance.com again. i already had to rewire the harness for the o2's when i first got it. it was popping fuses right out of the box.

at least i have the ability to scan now~!!!! i'm very pleased with that.
so i get the scan done, and......nothing.... no codes..... so i scan it again... and the only code it pulled was " 15 - coolent temp sensor low" . the sensor is not hooked up at all right now. it's still on the water pump.

so... what else can i do here. i have fuel, spark, no dtc's that i can see other then that one, and still no pulse to the injectors.