Code h36= opti death?
Thread Starter
Instructor
Joined: Jan 2003
Posts: 129
Likes: 0
From: Ontario ca
Code h36= opti death?
Ok so first off I have a 94 auto with about 140,000 miles and recently she started running rough, she would miss at part throttle, and every now and then her idle would slowly degrade until she shut off. So I checked codes and im showing an h36 (or what ever the bad high res signle code is) so after checking all my opti wires and then rechecking I cleared the codes and it poped up again; also she has been hard to start lately. So just as the title asks is my original 140,000 mile opti finaly on its way out?
Oh I almost forgot but Im also getting I think an H42 or what ever the ICM code is, but I fail to see how one code could cause the other.
Oh I almost forgot but Im also getting I think an H42 or what ever the ICM code is, but I fail to see how one code could cause the other.
Le Mans Master
Joined: May 2005
Posts: 7,299
Likes: 2,219
From: Central Maryland
High-res fault indicates a dying Opti, almost surely. The only other possibility that comes to mind is a connection fault from the Opti to the ECM on the high-res signal line.
Be well,
SJW
Be well,
SJW
Burning Brakes
Joined: Nov 2005
Posts: 1,211
Likes: 2
From: Dumas Arkansas
I'm sure if you do a search on my threads you'll find the code 36 problems that I had. The mechanic I the stealership replace the coil wire and not the opti which I believe they only charged me around $200
I haven't had any trouble since. Knock on wood.
I haven't had any trouble since. Knock on wood.
Le Mans Master
Joined: May 2005
Posts: 7,299
Likes: 2,219
From: Central Maryland
Originally Posted by slicked25
I'm sure if you do a search on my threads you'll find the code 36 problems that I had. The mechanic I the stealership replace the coil wire and not the opti which I believe they only charged me around $200
I haven't had any trouble since. Knock on wood.
I haven't had any trouble since. Knock on wood.
If anyone has a guess as to how a faulty coil wire could cause a high-res Opti fault, I'd love to hear about it.
Be well,
SJW
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
SJ - you and me both.
There is no physical relationship between that code and the coil wire...
UNLESS - the bad coil wire was causing such a consistant missfire, that the ECM could no longer adjust, the Opti threw up its hands in disgust and threw a code, because it could no longer do what it was asked to do.
It's a stretch, but sorta believable...
There is no physical relationship between that code and the coil wire...
UNLESS - the bad coil wire was causing such a consistant missfire, that the ECM could no longer adjust, the Opti threw up its hands in disgust and threw a code, because it could no longer do what it was asked to do.
It's a stretch, but sorta believable...
Le Mans Master
Joined: May 2005
Posts: 7,299
Likes: 2,219
From: Central Maryland
Originally Posted by bogus
SJ - you and me both.
There is no physical relationship between that code and the coil wire...
There is no physical relationship between that code and the coil wire...
Originally Posted by bogus
UNLESS - the bad coil wire was causing such a consistant missfire, that the ECM could no longer adjust, the Opti threw up its hands in disgust and threw a code, because it could no longer do what it was asked to do.
It's a stretch, but sorta believable...
It's a stretch, but sorta believable...
Unless I'm seriously misinformed about some of this:
1. Any post-combustion adjusting the ECM would be doing would be based only upon inputs from the O2 sensors and/or knock sensors. The ECM would be only adjusting fuel trim based upon O2S inputs, and only retarding spark timing based upon KS inputs.
2. Aside from distributing spark, all the Opti does is send to the ECM pulses that are derived from the optical sensors & triggerwheel. It isn't asked to do anything by the ECM, and it doesn't have any adaptive functionality. It has no capability to receive or act upon input of any kind from the ECM.
Be well,
SJW
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
The orignal '92 Opti-Spark extension harness had an extra pin in the connector and a shield around the cable.
That high voltage wire runs very close to the Opti-Spark extension harness.
My guess is the high-voltage from the ignition wiring was arcing into the '94 shield-less harness.
Let's face it, that shield can't hurt anything -- but, it seems GM decided that in later LT1s it wasn't needed.
After I converted my '92 to the later shield-less extension harness, I always make sure the coil wire is as far as possible from the Opti-Spark harness.
Tom Piper
That high voltage wire runs very close to the Opti-Spark extension harness.
My guess is the high-voltage from the ignition wiring was arcing into the '94 shield-less harness.
Let's face it, that shield can't hurt anything -- but, it seems GM decided that in later LT1s it wasn't needed.
After I converted my '92 to the later shield-less extension harness, I always make sure the coil wire is as far as possible from the Opti-Spark harness.
Tom Piper
Last edited by Tom Piper; Jun 5, 2006 at 02:45 PM.
Le Mans Master
Joined: May 2005
Posts: 7,299
Likes: 2,219
From: Central Maryland
Originally Posted by Tom Piper
The orignal '92 Opti-Spark extension harness had an extra pin in the connector and a shield around the cable.
That high voltage wire runs very close to the Opti-Spark extension harness.
My guess is the high-voltage from the ignition wiring was arcing into the '94 shield-less harness.
Let's face it, that shield can't hurt anything -- but, it seems GM decided that in later LT1s it wasn't needed.
After I converted my '92 to the later shield-less extension harness, I always make sure the coil wire is as far as possible from the Opti-Spark harness.
Tom Piper
That high voltage wire runs very close to the Opti-Spark extension harness.
My guess is the high-voltage from the ignition wiring was arcing into the '94 shield-less harness.
Let's face it, that shield can't hurt anything -- but, it seems GM decided that in later LT1s it wasn't needed.
After I converted my '92 to the later shield-less extension harness, I always make sure the coil wire is as far as possible from the Opti-Spark harness.
Tom Piper
Be well,
SJW
