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No Spark No start

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533 views 22 replies 5 participants last post by  TealHornet  
#1 ·
Howdy guys, I'm seeking assistance with a no spark no start issue on my 97 trans am. Here is the back story. I'm going to include as much details as I can, some may not be helpful but I'm going to include everything I know. I bought the car last spring. The previous owner changed the car over to individual coil packs with an ls1 pcm. It appears to be a complete kit from torquehead. The car ran upon purchasing, but it did have an occasional problem idling properly. but the wiring was wretched. Wires were ran loose in the engine bay, exposed conductors, no plastic conduit etc... I began repairing the wiring late spring early summer then it got shelved because it was so hot outside. Last week I resumed the project and finished the wiring repairs. I plugged everything back together, triple checked everything, charged the battery up, and went to start it, and it wouldn't. It cranks just fine; I hear the fuel pump kick on and fuel rail pressure is good. I checked for spark, and it didn't have any. I checked for 12v at the coils with the ignition in the start position and there was no voltage on the pink wire or any wire for that matter. I ohmed out every fuse and checked voltage at all the fuse holders, it is all good. I checked all the grounds on the car and ohmed all of them out as well. From what i can tell it is not a ground or fuse problem. I looked at a pin diagram for the pcm connectors and what I saw was on connector c2 black pin 31 orange wire 340 was pcm power, I checked that, and it has 12v, so the pcm should have power. There was a couple of splices I Made to repair what was previously done and I Ohmed them out as well, they were all good. I have a basic scanner from harbor freight it said there were no codes. I read somewhere about the vats being a potential I haven't dove into that yet but the security light does not stay on. I have no experience with these cars whatsoever. I am however an electrician by trade. Please correct me if anything I said was inaccurate, and please help LOL TIA
 
#7 ·
Where is this ignition relay? I’ve heard people mention it and even say that it’s in the underhood fuse box, but it is not at, least on my car. I’ve located the two relays under the glove box is it one of those? If you could share some more details about your resolution that would be awesome, TIA
 
#12 ·
If your security light goes out shortly after turning ignition on, and your not getting a blinking red light on dash, then VATS probably isn’t the issue although never say never.

You can rent from autozone or oriellys a fuel injector light kit that you disconnect your injector and plug this into each injector one at a time, cranking the ignition, and if your Injectors are getting voltage they will pulse.

Since you know it did run except an idle issue, and it sat for a long while I’d be willing to say you have an injector issue! Injectors can become plugged up from just sitting. One way to know for sure is unbolt the fuel rail and while someone cranks it and see what is spraying and what’s not. You might be surprised!

Have you tried spraying starter fluid with lubrication in it, to see if it will start/run briefly?! If you do unbolt it and you have clogged injectors or poor spray on some, send them off to be rebuilt cleaned and flow matched. Buying new doesn’t mean good.

worth a shot to try…ask me how I know 🤣

Dave
 
#13 ·
Vats is car alarm .
so you should know there is adjuster for how easy alarm can go off rear passenger wheel well where spare goes
settings 1-10 I think
its tied to key FOB and transistor in key
if it doesnt detect key it kills injector pulse
also in heavy wreck it will also kill fuel maybe at pump too
easy way to find fuel relay if its working is to stick head under hood and have some one else turn key to on
it will click
 
#14 ·
Vats is car alarm .
so you should know there is adjuster for how easy alarm can go off rear passenger wheel well where spare goes
settings 1-10 I think
its tied to key FOB and transistor in key
if it doesnt detect key it kills injector pulse
also in heavy wreck it will also kill fuel maybe at pump too
easy way to find fuel relay if its working is to stick head under hood and have some one else turn key to on
it will click
I have a VATS box on passenger wheel well from factory but there is no way to adjust it and from what I know of. I have never taken it apart however to look inside.

Also the fuel pump relay on a 97 LT1 is on or rather under drivers side kick panel secured to a small bracket by itself, it isn’t under hood. I don’t where it is located on previous years though.
 
#15 ·
you should have same adjuster as me your vats is directly behind your radio on center fire wall under dash
I think its
3 inch by 4 inch black box with wiring piled on top and others going in .
Im not a expert though.
you also should put new battery in your remote and try unlocking doors the other way to shut off alarm is key in ignition and turning to on .
Vats disconnects injectors when car alarm trips.
I dont think it has any thing to do with ignition
I do know when you splice wire do a 2 hand crimp crunch
and the power may not get past a crimp you need to check at plugs to make sure power is making it past it
Gm wire to GM wire not some crap chinese splice in they dont conduct so any thing like that is no no
stick to delco every thing
 
#16 ·
you should have same adjuster as me your vats is directly behind your radio on center fire wall under dash I think its a3 inch by 4 inch black box with wiring piled on top and others going in .
Im not a expert though.
.
You may not be an “expert” but you are Very knowledgeable and willing to help and that’s what makes a difference! I’ve read a lot of good advise such your post I quoted this from.

Also, I do know the black box you are referring to now, I ve got an extra from another 97 parts car I had, so I gonna locate it and open her up to check her out inside as I was unaware of this capability.

Oh and you mentioned crimping wires, I’ve used those slip on butt to butt solder joints that you can heat them up and solder melts into wires that effectively joins them and the outside casing acts like shrink wrap. They work fantastic and never have had an issue yet but like you say buy quality not chinesium is key!

Dave
 
#17 ·
Dont they dont like being tampered with and you may cause issues with that box recognizing key
the security light coming on is a circuit check it going off is aok just like the obd1 and 2
Either bypass or dont touch
you need to focus on your ignition circuit and injector pulse circuit
you take and tackle 1 problem at a time.
its a process you dont run problem crank no start focus
gas or spark ?
1 first spray either in throttle body and crank engine does it start ???
it started fuel injection issue
no start its spark
stay with me
 
#18 ·
I just been trouble shooting multiple Cadillac's and mickey moused implant and get confused some times but i am focused on you.
I need your answer on fuel or ignition
But im gona jump ahead for a second .
You said you have no power on your pink wire
you have 2 pink wire circuits 1 is your AC AIR COND.
THAT WONT HAVE POWER UNLESS AC is on and key is turned to on .
pink ignition circuit power goes to ignition control module-crank shaft position sensor - Ignition coil -electronic ignition control module thes run to direct power fuse box under hood .
fuse 11 key has to be on so a good way to work on electrical like this you want a charger on battery..
if below 11 volts or so cpu will kill circuit 10.5ish.
fuse 11 pull fuse and look at fuse map is in cover make sure your not upside down check element in fuse .
fuse is 32 years old tainted at the least sand paper the terminals and the terminals it plugs into and blow them out .
or scrape them with something thin best you can and if handy change to new 10 amp fuse .
you can get bottle necking power from your power cable also if it is dirty at terminal or in line .
that means it hesitates and can show 12 volts but no real amperage and has to burn through crap and take a minute just to turn on small light.
so now you have power at both sides of fuse
now check key on at coil -ignition module - crank sensor - electronic control modual last
crank sensor is probably your opti or on bottom with test light to proven ground
pink wire on the plug you dont want to put 12 volts to other wires
you can also crank and see pulse on light on crank sensor..
 
#19 ·
you also have pinks going in 2 other branches to power all sensors
this might be wild goose chase they might be talking about cpu 93 obd1 was behind glove compartment 97 is under hood but they said a ignition relay is behind glove box
at shoebox they talk about ignition switch powering pcm ignition circuit im not sure where my ignition relay and fuel relay were mounted but now they are zip tied to steering column.
But im thinking tapp on them see if you get power here the ignition switch stuff from
Shoe box
http://shbox.com/ignsw/ign_switch_repl.html
 
#23 ·
copied from shoebox

Here is some testing you can do. Refer to this diagram for 94-95s. 93 and 96-97 ignition system diagrams are slightly different overall, but the ICM connector is the same. Note: Pay attention to the fact that the diagram may show A-B-C-D out of order for ease of diagramming. They are actually in proper order on the physical connector. The connector has the letters embossed on it, so make sure you are testing the correct one.

Disconnect the ICM connector. Leave coil connected (important).

Turn key to ON.

Check for dc voltage with a digital meter at harness terminal "A" to ground and and also "D" to ground. Note: Use a modern digital meter with at least 10 megohm impedance to protect the PCM (in case you measure anything in that direction). Do not use a test light for looking at voltage potentials from electronics! Also make sure your meter leads make good contact and are clean and tight. Check that you get a zero ohms reading by touching the two leads together. If it is not zero, merely adjust the readings you take by the skew. That will ensure accurate resistance readings.

Result should be 10v dc or more on the A and D terminals. If you get no voltage, use the diagram and chase back toward the coil and the ignition fuse. Power for the ICM comes from the ignition fuse and through the coil, so any of that could be bad.
If you have good voltage, switch the meter to ac scale and connect test leads to terminal "B" and to ground. Observe meter while cranking the engine. You should see between 1 and 4 volts ac (those are the pulses that trigger the coil to fire).

If you don't see the proper ac voltage the problem could be the optispark, the harness to the optispark, the PCM (not common) or any of the wiring in between. Visually inspect all the connections for possible poor contact or corrosion.

You should also check "C" of the ICM harness for continuity to ground.

ICM Harness

A = ~10vdc-12vdc (or your system voltage)
B = 1vac-4vac while cranking
C = ~ 0 ohms to ground with key OFF
D = ~10vdc-12vdc (or your system voltage-might be slightly less than reading at "A")


At the end of the optispark harness (disconnected from the opti) with the key ON, you should see:

Optispark Harness

A = ~5vdc
B = ~5vdc
C = ~12vdc (or your system voltage)
D = ~0 - 0.2 ohms ground with key OFF

If you have the means, looking at the low and high resolution signals from the opti to the PCM with an oscilloscope is probably the best way to tell their health.

edited 9/19/2023