Have codes, Need help!
Thread Starter
Instructor
Joined: Jan 2004
Posts: 103
Likes: 0
From: Corpus Christi TX
Have codes, Need help!
Last night I pulled the codes off my 94 coupe, because the sys is blinking at me. Here's what I got: C34, H33, and H34. Does anyone know the difference between an H and a C code. I know one of them has to do with the MAP sensor, but that's it. I would appreciate your input. :flag
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Re: Have codes, Need help! (nvlav8tor)
I can't answer your question, :( but you might want to go to http://www.c4vettes.com/ecm.htm-I have no idea what the letters account for :rolleyes: I suspect the codes themselves are what you should focus on.
GOOD LUCK :seeya
Thread Starter
Instructor
Joined: Jan 2004
Posts: 103
Likes: 0
From: Corpus Christi TX
Re: Have codes, Need help! (rick lambert)
Thanks Rick, but that site is currently down for construction. Or, I might be using it wrong. Do you know what link I should click on? :flag
Burning Brakes
Joined: Apr 2001
Posts: 994
Likes: 0
From: Jamison PA
Re: Have codes, Need help! (nvlav8tor)
Don't know if a 94 is the same as a 96 but "sys" codes 33 and 34 deal with the data clock. 33 is Data clock circuit shorted to B+ or CCM internal open. 34 is Data clock circuit open or shorted to ground. "H" I think stands for history readout and "C" stands for current readout. Hope this helps.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Have codes, Need help! (nvlav8tor)
C means current; H is history so it's no longer present. You can clear them and see what comes back - should be the 33, but it's curious that you had both. These are MAP codes. How's performance/idle? The 34 means the idle voltage was high when it should have been low. It can be a bad ground but with both codes, you might suspect the reference wire or PCM (which depending on your mileage, might just be covered under the Fed Emissions warranty). Gray is the 5 volt reference. Green is the return. Black is ground. MAP range is 1 to about 4.8 volts. At idle, it should be about 1 to 1.5; WOT 4.5 to 4.8. The 33 means the voltage remained low with engine speed above 700 rpm, so another suspect would be the green wire, the connector or the MAP itself. As to the wiring, no-one spliced in a new harness did they? I only mention this because I experienced this once - some idiot (who will remain nameless of course) crimped in a new harness after breaking the MAP connector. the crimp loosened creating an intermittent stall that took two dealers plus the original DIY to diagnose. You're lucky to have codes - check the wiring carefully.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski