C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1994 - Recurring H34 Code

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Old Aug 14, 2016 | 12:52 PM
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Default 1994 - Recurring H34 Code

Okay so last weekend I re-bled all the brakes using the gravity bleed method. Now, everytime I drive the car I get code 34. The SYS light comes on and goes off in about 30 seconds. I notice no issues, no poor performance, etc... Everything seems fine. Except for the stupid SYS light that comes and goes. I get home break out the paper clip and get a code H34 in module 4.

34 = MAP sensor low voltage (correct me if I am wrong).

I know this can't be related to me re-bleeding the brakes. Does anybody have any ideas? All wiring seems fine but I will be glad to take another look. I've always heard the MAP sensors on these cars are pretty robust and rarely ever go bad.
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Old Aug 14, 2016 | 09:55 PM
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Clear the code and see if it comes back it might not be related. My 94 would flash the light setting no codes. I changed the front o2s no more light and ran better than ever. They get old and slow and are normal maintenance. How many miles?
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Old Aug 15, 2016 | 09:44 PM
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Even though it's a history code, I would still follow the diagnostic in the FSM. Did you ever get aldldriod working? Might need it for a MAP problem. If you're dataloging, the MAP numbers should go up when you accelerate. If not, I would say it's bad. But IIRC, the FSM has a weird diagnostic for the MAP sensor.

Last edited by 1993C4LT1; Aug 15, 2016 at 11:11 PM. Reason: Read it as MAF problem
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Old Aug 15, 2016 | 10:53 PM
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DTC34 is for the MAP sensor, like he stated, not the MAF sensor.

With that code, it sounds like it is unplugged or there is a bad connection at the sensor. Is it anywhere near where you were working?
Or it could be just a defective sensor.

Last edited by GaryDoug; Aug 15, 2016 at 10:55 PM.
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Old Aug 16, 2016 | 08:24 AM
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antfarmer- 02's are fine. Were replaced 5,000 miles ago. How do we go from bleeding brakes, to an actual code that corresponds to the MAP sensor, to 02 sensors again? Why?

Brandon- ALDL droid is still something I would like to do.

Gary-Thanks for the input. I went back and reinspected the MAP sensor and noticed the clip on the connector is broken off. Seems to still be holding fine but I want to repair this to rule anything out before continuing further. I unhooked the battery for 30 minutes and then drove the car for 2 hours on Sunday afternoon and the SYS light never came back on.
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Old Aug 28, 2016 | 11:08 AM
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Problem Solved. Fixed the connector. I have driven it 300+ miles and no more light or code stored.








Last edited by TorchTarga94; Aug 28, 2016 at 11:09 AM.
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Old Aug 28, 2016 | 01:52 PM
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Oh hell yea! My connector looks like the one in your last pic, but I won't fix it till messes up.
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Old Aug 31, 2016 | 09:21 AM
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I like posts that have a a followed up (This is how I fixed it.) So often especially in Sys Admin forums you see "I got this problem" and 20 suggestions go out and the person never posts "Yeah it was this and here is how I fixed it."

Thanks for posting that "Your" issue was resolved and how and what you did to resolve it... This helps us all in the long run.
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Old Aug 31, 2016 | 09:33 AM
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Absolutely I try to do that as much as possible. I also referred to this video for re-pinning the connector. Made much more sense than buying a pigtail connector and soldering one in.


This guy has a few loose screws but good info:

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Old Sep 4, 2016 | 07:19 PM
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H34 came back tonight.

Really hate this car...

Last edited by TorchTarga94; Sep 11, 2016 at 10:47 PM.
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