8 Ignition Modules later
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Safety Car
Joined: Jul 2004
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I had an '86 with a similar issue - no spark, I changed the ignition module which fixed it briefly, then the same problem came back - I finally traced it to an intermittent open in the small wiring harness that goes from the 5-pin end of the ignition module out the side of the distributor to a larger 4-pin connector that connects to the harness running along the firewall.
This small harness has 4 wires, 3 of which connect to the ignition module, the 4th is grounded by a screw to the base of the distributor. (Sorry for the extensive description - Just trying to make sure we all know what I'm talking about).
Anyway, the act of replacing the ignition module jiggled these wires enough that it would work for a while, then act up again. I got to where I'd just tug on the wires and the problem would go away.
This small harness has 4 wires, 3 of which connect to the ignition module, the 4th is grounded by a screw to the base of the distributor. (Sorry for the extensive description - Just trying to make sure we all know what I'm talking about).
Anyway, the act of replacing the ignition module jiggled these wires enough that it would work for a while, then act up again. I got to where I'd just tug on the wires and the problem would go away.
Melting Slicks
Joined: Feb 2006
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From: backwoods upstate ny
no, ohm meters (aka volt/ohm meter or VOM) typically use very small current to test...even a single strand in wire or a corroded connector may look fine to a miniscule current flow but that conductor will not handle higher current flow satisfactorily...this is why the Service Manual often will say to test with a test lamp (not because the stealerships do not have VOM's)
Last edited by redrose; Jul 18, 2008 at 06:26 PM.
Thread Starter
Safety Car
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...i have both an ohm meter as well as a vtvm that will definetly do the trick........
Melting Slicks
Joined: Feb 2006
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From: backwoods upstate ny
Advanced
Joined: May 2006
Posts: 70
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From: Davisburg Michigan
.....thanks for the reply...i was moving the wires around a few times when this hapened to me in the past and didn't see any results...thank god that i had/have a life warranty on the ignition module!...do you have or can obtain a part number for the part that you are describing?...it should exit the distributor housing near the "rear"(firewall area) of the distributor as the other condenser assembly exits out the "front".....
p/n is 01986260 "Terminal Block" and just so you're warned, the price is a bit staggering. (Around $100
) I believe the same p/n is used across most GM stuff of similar vintage with a similar EST system, so a trip to the local you-pull-it junkyard might be a good idea if you want to try throwing this particular part at it.
Thread Starter
Safety Car
Joined: Jul 2004
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.....i plan on it...went to school for electronics and was briefly in the repair business on the side....haven't don't any in years...used to be an electrician by trade too....(i always like the tube amps as they always produced a richer sound and can take a pounding).....btw, what is "btdt" ?
Thread Starter
Safety Car
Joined: Jul 2004
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Yes, the wires exit out the back of the distributor.
p/n is 01986260 "Terminal Block" and just so you're warned, the price is a bit staggering. (Around $100 )
I believe the same p/n is used across most GM stuff of similar vintage with a similar EST system, so a trip to the local you-pull-it junkyard might be a good idea if you want to try throwing this particular part at it.
p/n is 01986260 "Terminal Block" and just so you're warned, the price is a bit staggering. (Around $100
) I believe the same p/n is used across most GM stuff of similar vintage with a similar EST system, so a trip to the local you-pull-it junkyard might be a good idea if you want to try throwing this particular part at it.
Yes, the wires exit out the back of the distributor.**i am aware of that...seems to be they could have come up with a better design..
p/n is 01986260 "Terminal Block" and just so you're warned, the price is a bit staggering. (Around $100 ) **damn!, the capacitor assembly i just replace was quoted at about $35 from the dealer and about $11 at auto-zone...is this a gm part number?
I believe the same p/n is used across most GM stuff of similar vintage with a similar EST system, so a trip to the local you-pull-it junkyard might be a good idea if you want to try throwing this particular part at it. **i may have to do that..i have a large amount of intake manifolds, distributors, holley and carter carbs in my garage that were once my deceased best friends stuff...he used to experiment a lot as to what gave him better performance and so on...maybe i'll pull out a distributor and see what's up, however, i hate to tear into an almost brand new distributor!...ugh!
Last edited by Da Mail Man; Jul 18, 2008 at 07:27 PM. Reason: spelling error
Melting Slicks
Joined: Feb 2006
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From: backwoods upstate ny
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Thread Starter
Safety Car
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Advanced
Joined: May 2006
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From: Davisburg Michigan
**************************
Yes, the wires exit out the back of the distributor.**i am aware of that...seems to be they could have come up with a better design..
p/n is 01986260 "Terminal Block" and just so you're warned, the price is a bit staggering. (Around $100 ) **damn!, the capacitor assembly i just replace was quoted at about $35 from the dealer and about $11 at auto-zone...is this a gm part number?
I believe the same p/n is used across most GM stuff of similar vintage with a similar EST system, so a trip to the local you-pull-it junkyard might be a good idea if you want to try throwing this particular part at it. **i may have to do that..i have a large amount of intak manifolds, distributors, holley and carter carbs in my garage that were once my deceased best friends stuff...he used to experiment a lot as to what gave him better performance and so on...maybe i'll pull out a distributor and see what's up, however, i hate to tear into an almost brand new distributor!...ugh!
Yes, the wires exit out the back of the distributor.**i am aware of that...seems to be they could have come up with a better design..
p/n is 01986260 "Terminal Block" and just so you're warned, the price is a bit staggering. (Around $100 ) **damn!, the capacitor assembly i just replace was quoted at about $35 from the dealer and about $11 at auto-zone...is this a gm part number?
I believe the same p/n is used across most GM stuff of similar vintage with a similar EST system, so a trip to the local you-pull-it junkyard might be a good idea if you want to try throwing this particular part at it. **i may have to do that..i have a large amount of intak manifolds, distributors, holley and carter carbs in my garage that were once my deceased best friends stuff...he used to experiment a lot as to what gave him better performance and so on...maybe i'll pull out a distributor and see what's up, however, i hate to tear into an almost brand new distributor!...ugh!
That part number is GM / AC Delco - I never found the same part available aftermarket.
I peeked inside a few HEI distributors I had in my collection, too, but most were earlier vacuum or mechanical advance models which don't use this harness. They have a different Ignition Module, which looks almost the same except it's missing a few wires/connections. I'd guess that if you find another distributor with that big flat 4-pin connector hanging out the back, you're good.
Basically, the harness in question carries the Electronic Spark Timing signal between the Ignition Module and the Engine Control Module through the 'baked' connector. The other two wires on the 5-pin side of the Ignition Module come from the pick up coil inside the base of the distributor, underneath the rotor.
Thread Starter
Safety Car
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I agree on the location being awful - stuffing it back there and letting it bake certainly isn't the best design for reliability.
That part number is GM / AC Delco - I never found the same part available aftermarket.
I peeked inside a few HEI distributors I had in my collection, too, but most were earlier vacuum or mechanical advance models which don't use this harness. They have a different Ignition Module, which looks almost the same except it's missing a few wires/connections. I'd guess that if you find another distributor with that big flat 4-pin connector hanging out the back, you're good.
Basically, the harness in question carries the Electronic Spark Timing signal between the Ignition Module and the Engine Control Module through the 'baked' connector. The other two wires on the 5-pin side of the Ignition Module come from the pick up coil inside the base of the distributor, underneath the rotor.
That part number is GM / AC Delco - I never found the same part available aftermarket.
I peeked inside a few HEI distributors I had in my collection, too, but most were earlier vacuum or mechanical advance models which don't use this harness. They have a different Ignition Module, which looks almost the same except it's missing a few wires/connections. I'd guess that if you find another distributor with that big flat 4-pin connector hanging out the back, you're good.
Basically, the harness in question carries the Electronic Spark Timing signal between the Ignition Module and the Engine Control Module through the 'baked' connector. The other two wires on the 5-pin side of the Ignition Module come from the pick up coil inside the base of the distributor, underneath the rotor.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Well at least you've eliminated the ign. control module as the culprit.
4-5 years ago I had my dist. out, re-installed it and accidentally clamped that short wire harness under the base of the dist. needless to say I had a problem. Called the stealership...no longer available for my 87....BUT, they had one for a caddy, $95. never again, I'd go to a wrecking yard and pull one out.....if it checked out bad! Would have been nice if it were 4-5 inches longer and attacthed to the firewall.
4-5 years ago I had my dist. out, re-installed it and accidentally clamped that short wire harness under the base of the dist. needless to say I had a problem. Called the stealership...no longer available for my 87....BUT, they had one for a caddy, $95. never again, I'd go to a wrecking yard and pull one out.....if it checked out bad! Would have been nice if it were 4-5 inches longer and attacthed to the firewall.
Thread Starter
Safety Car
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Well at least you've eliminated the ign. control module as the culprit.
4-5 years ago I had my dist. out, re-installed it and accidentally clamped that short wire harness under the base of the dist. needless to say I had a problem. Called the stealership...no longer available for my 87....BUT, they had one for a caddy, $95. never again, I'd go to a wrecking yard and pull one out.....if it checked out bad! Would have been nice if it were 4-5 inches longer and attacthed to the firewall.
4-5 years ago I had my dist. out, re-installed it and accidentally clamped that short wire harness under the base of the dist. needless to say I had a problem. Called the stealership...no longer available for my 87....BUT, they had one for a caddy, $95. never again, I'd go to a wrecking yard and pull one out.....if it checked out bad! Would have been nice if it were 4-5 inches longer and attacthed to the firewall.
Thread Starter
Safety Car
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i have this placed in the "want to buy section" of the forum should anyone read this particular post;
#############################
...for an 88 vettte (of course!)..here is a description to orient you to the part i am looking for;
inside the distributor is (in part) the ignition module...one side of the ignition module has a capacitor/condenser assembly that plugs into the ignition module on one side, goes through the condensor assembly and exits out of the distributor housing..
****at the other side of the ignition module there is another plug(s) that connects to it and that too also exits the distributor..THAT IS THE PART I NEED.... it is not the part with the "round thing" some had refered to it as nor is it the pick up coil assembly nor the coil....
if anyone has one in good shape that fits the STOCK 88 "est" distributor, please get back to me as i am trying to eliminate a years-long problem i am having and need for test purposes...THANKS!....
#############################
...for an 88 vettte (of course!)..here is a description to orient you to the part i am looking for;
inside the distributor is (in part) the ignition module...one side of the ignition module has a capacitor/condenser assembly that plugs into the ignition module on one side, goes through the condensor assembly and exits out of the distributor housing..
****at the other side of the ignition module there is another plug(s) that connects to it and that too also exits the distributor..THAT IS THE PART I NEED.... it is not the part with the "round thing" some had refered to it as nor is it the pick up coil assembly nor the coil....
if anyone has one in good shape that fits the STOCK 88 "est" distributor, please get back to me as i am trying to eliminate a years-long problem i am having and need for test purposes...THANKS!....
Last edited by Da Mail Man; Jul 20, 2008 at 09:32 PM. Reason: spelling error
Racer
Joined: Dec 2000
Posts: 385
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From: Blue Ridge GA
....in the past 3 years i have gone through 8 ignition modules in my distributor (another yesterday)
and cannot figure out as to why this is happening....coil is new, rotor, cap, wires, etc all new.....
People on this board told me it was because of my MSD and remote coil, pick up coil, and wires. I even put in a new Accel distributor which has the new wires in it and it still blows. I've put everything back to stock and they still blow.
They told me that cheap aftermarket IMs are junk, so I spent big bucks on the factory ones, they still blow. Now I have lifetime warranty ones and just keep getting new one every 6 months. I've gotten to where I can swap them out in about 10-15 minutes. But it is a real pain when it happens in the rain.
I hope someone on here can get a real handle on this issue. Perhaps I need a new ECM?
Last edited by Stealthvette; Aug 4, 2008 at 06:38 PM.
Thread Starter
Safety Car
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I've had the same issue for 8 years IMs going out every 6 months like clockwork in my 86 coupe. I always carry a spare. I can tell when it has blown, when I key the ignition, the fuel pump doesn't cycle. Put in the new IM and I'm good to go for another 6 months.
***that in itself is strange...regardless if the module is bad or not, the fuel pump should still activate (prime)!
People on this board told me it was because of my MSD and remote coil, pick up coil, and wires. I even put in a new Accel distributor which has the new wires in it and it still blows. I've put everything back to stock and they still blow.
***if you have read this thread, you'll see that all mine is stock and my modules still "blow"...
They told me that cheap aftermarket IMs are junk, so I spent big bucks on the factory ones, they still blow. Now I have lifetime warranty ones and just keep getting new one every 6 months. I've gotten to where I can swap them out in about 10-15 minutes. But it is a real pain when it happens in the rain.
***i had changed all mine under warranty and never had them tested, just merely took 'em back and exchanged them...somehow, they may have all actually been good!..at any rate, the last one that i though was blown (oem delco gm) i did bring in and test and ran it through over 10 test cycles and the module tested good...i have since replaced the capacitor assembly (previous thread aforementioned) so, all i can do is wait and see how long it lasts..i too carry a spare!
I hope someone on here can get a real handle on this issue. Perhaps I need a new ECM?
***doubt ecm!
***that in itself is strange...regardless if the module is bad or not, the fuel pump should still activate (prime)!
People on this board told me it was because of my MSD and remote coil, pick up coil, and wires. I even put in a new Accel distributor which has the new wires in it and it still blows. I've put everything back to stock and they still blow.
***if you have read this thread, you'll see that all mine is stock and my modules still "blow"...
They told me that cheap aftermarket IMs are junk, so I spent big bucks on the factory ones, they still blow. Now I have lifetime warranty ones and just keep getting new one every 6 months. I've gotten to where I can swap them out in about 10-15 minutes. But it is a real pain when it happens in the rain.
***i had changed all mine under warranty and never had them tested, just merely took 'em back and exchanged them...somehow, they may have all actually been good!..at any rate, the last one that i though was blown (oem delco gm) i did bring in and test and ran it through over 10 test cycles and the module tested good...i have since replaced the capacitor assembly (previous thread aforementioned) so, all i can do is wait and see how long it lasts..i too carry a spare!
I hope someone on here can get a real handle on this issue. Perhaps I need a new ECM?
***doubt ecm!
Thread Starter
Safety Car
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...UPDATE;
..i figured that i would get back to this thread...i have long since put in a replacement ignition module and all is working fine!....
....the inside of the distributor is just as clean as the day it came from the factory....HOWEVER, what i did is sand down the base where the wire attaches to the base of the distributor and remove the "shine"....what i conclude is that the clean finish was setting up a high resistance which could have been the problem all along!..UGH!
..i figured that i would get back to this thread...i have long since put in a replacement ignition module and all is working fine!....
....the inside of the distributor is just as clean as the day it came from the factory....HOWEVER, what i did is sand down the base where the wire attaches to the base of the distributor and remove the "shine"....what i conclude is that the clean finish was setting up a high resistance which could have been the problem all along!..UGH!
