Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Sponsored by:
Sponsored by: CARiD

Cranks, but no spark

Thread Tools
 
Search this Thread
 
Old Oct 14, 2019 | 11:15 AM
  #1  
babadioum's Avatar
Thread Starter
Member
15 Year Member
Liked
 
Joined: Mar 2009
Posts: 133
Likes: 2
From: 10K miles away from home (SF, CA)
Car: 1991 CHEVROLET CAMARO Z28
Engine: 6 LITER after rebuilding :)
Transmission: 700 R4
Axle/Gears: 3.23 / 9:7:1
Cranks, but no spark

I'm not getting any spark from the coil-to-distributor cable, that should most probably point to a faulty coil, correct? IF my ICM was faulty, I'd get spark at the coil-to-distributor cable end, wouldn't I? Thanks in advance

Last edited by babadioum; Oct 14, 2019 at 11:16 AM. Reason: mispelling
Reply
Old Oct 14, 2019 | 11:23 AM
  #2  
ironwill's Avatar
Supreme Member
15 Year Member
 
Joined: Jan 2008
Posts: 1,331
Likes: 565
Car: 1986 IROC Z
Engine: 5.0 TPI
Transmission: 700R4
Axle/Gears: 3.23 Posi
Re: Cranks, but no spark

Originally Posted by babadioum
I'm not getting any spark from the coil-to-distributor cable, that should most probably point to a faulty coil, correct? IF my ICM was faulty, I'd get spark at the coil-to-distributor cable end, wouldn't I? Thanks in advance
If the ICM is at fault, there will be no spark at all. If you don't have a factory shop manual, you can find ICM troubleshooting steps here: https://easyautodiagnostics.com/gm/4...ed-icm-tests-6
Reply
Old Oct 14, 2019 | 11:27 AM
  #3  
babadioum's Avatar
Thread Starter
Member
15 Year Member
Liked
 
Joined: Mar 2009
Posts: 133
Likes: 2
From: 10K miles away from home (SF, CA)
Car: 1991 CHEVROLET CAMARO Z28
Engine: 6 LITER after rebuilding :)
Transmission: 700 R4
Axle/Gears: 3.23 / 9:7:1
Re: Cranks, but no spark

Thanks, I'll check it out So then, 1) coil, OR, 2) ICM can be faulty, correct? I mean, assuming ICM is OK, but coil is faulty, I'd still wouldn't get spark, correct?
Reply
Old Oct 14, 2019 | 11:34 AM
  #4  
Tuned Performance's Avatar
Sponsor
20 Year Member
Community Builder
Community Influencer
Community Favorite
iTrader: (94)
 
Joined: Dec 2004
Posts: 16,740
Likes: 994
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: Cranks, but no spark

If the coil is bad it can’t produce spark. Go through the trouble shooting link.
start with check power to the icm key on at the pink wire at the icm connector.
Reply
Old Oct 14, 2019 | 11:49 AM
  #5  
ironwill's Avatar
Supreme Member
15 Year Member
 
Joined: Jan 2008
Posts: 1,331
Likes: 565
Car: 1986 IROC Z
Engine: 5.0 TPI
Transmission: 700R4
Axle/Gears: 3.23 Posi
Re: Cranks, but no spark

Originally Posted by babadioum
Thanks, I'll check it out So then, 1) coil, OR, 2) ICM can be faulty, correct? I mean, assuming ICM is OK, but coil is faulty, I'd still wouldn't get spark, correct?
The coil gets it's signal from the ICM; both must be functional in order to produce ignition spark.

These are old cars, with old wiring and old connectors. Check everything, as directed in the link I provided before you throw parts---and $$$---at the car.
Reply
Old Oct 14, 2019 | 11:54 AM
  #6  
babadioum's Avatar
Thread Starter
Member
15 Year Member
Liked
 
Joined: Mar 2009
Posts: 133
Likes: 2
From: 10K miles away from home (SF, CA)
Car: 1991 CHEVROLET CAMARO Z28
Engine: 6 LITER after rebuilding :)
Transmission: 700 R4
Axle/Gears: 3.23 / 9:7:1
Re: Cranks, but no spark

will do the test
Reply
Old Oct 14, 2019 | 12:15 PM
  #7  
babadioum's Avatar
Thread Starter
Member
15 Year Member
Liked
 
Joined: Mar 2009
Posts: 133
Likes: 2
From: 10K miles away from home (SF, CA)
Car: 1991 CHEVROLET CAMARO Z28
Engine: 6 LITER after rebuilding :)
Transmission: 700 R4
Axle/Gears: 3.23 / 9:7:1
Re: Cranks, but no spark

Here is my dilemma: IF no voltage, pick-up coil is faulty; that's guaranteed, but IF there is voltage, ICM can still be OK while ignition coil is busted, so if there is voltage, the test is ONLY conclusive as long as I guarantee a working ignition coil, correct? So I must check the ignition coil FIRST and ensure it works, correct?

Last edited by babadioum; Oct 14, 2019 at 12:17 PM. Reason: wrong word
Reply
Old Oct 14, 2019 | 01:30 PM
  #8  
Tuned Performance's Avatar
Sponsor
20 Year Member
Community Builder
Community Influencer
Community Favorite
iTrader: (94)
 
Joined: Dec 2004
Posts: 16,740
Likes: 994
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: Cranks, but no spark

The pink wire goes from the ignition switch to the coil then onto the icm. It powers the coil and icm key one engine off.
if that’s fine remove the cap and check for voltage while cranking at the pu coil.
if that’s producing the correct voltage it’s the icm.
Reply
Old Oct 16, 2019 | 03:59 PM
  #9  
babadioum's Avatar
Thread Starter
Member
15 Year Member
Liked
 
Joined: Mar 2009
Posts: 133
Likes: 2
From: 10K miles away from home (SF, CA)
Car: 1991 CHEVROLET CAMARO Z28
Engine: 6 LITER after rebuilding :)
Transmission: 700 R4
Axle/Gears: 3.23 / 9:7:1
Re: Cranks, but no spark

Here is the scoop: the tests clearly exonerated the coil and p-u coil which left ICM as the sole culpable item, so I put the spare to no avail AND the test still pointed to ICM; since two busted ICMs in a row is almost very unlikely and since I was in the midst of a full harness replacement, adapting a swap kit from Payless 60103 which practically becomes an OEM replacement with few ECM and 15-way connector hook-ups based on the OEM mapping (I'll post the work later), I decided to first fix the SES light & ALDL circuitry, crank the engine and get the probable code(s) set so I can accurately pinpoint to the actual problem(s). After wrestling with few hiccups, I got the diagnostics circuitry working and received only the code 46 (VATS): Since the ECM line to VATS sensor was OK, that led me to a unhooked ground off the C7 bulkhead connector which I promptly fixed. Then cranked to no avail, so I circled back to the original ICM, the one I knew it was working before the whole overhaul started since I already identified the replacement also possibly faulty, and voila! Runs like never before
PS: Since VATS was the issue, the fuel was cut off which was probably having an effect on ICM circuitry, at least that's what I assumed for both being indicated as "faulty", but it turned out only one ICM was in fact faulty

Thank you all for your quick and helpful assistances.

Last edited by babadioum; Oct 16, 2019 at 04:00 PM. Reason: wording
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
mynameisfrank89
Tech / General Engine
9
Sep 26, 2016 07:59 PM
transamgta1Khp
Electronics
0
Aug 17, 2015 12:18 PM
86firebird350
TBI
35
Feb 16, 2013 08:04 AM
Alpha 1 [BAI]
Electronics
2
Jan 24, 2007 01:55 AM




All times are GMT -5. The time now is 05:50 PM.