Code 34 on 93 LT5 - ZR-1 Net Registry Forums

Jetjock · 1 Day Ago

Earlie, I had a code 33, 45 and 65. I changed out the MAP sensor, disconnected the battery, ran the engine and checked the codes again. This time, I got a code 34 and the other codes disappeared. I plan to run the car this afternoon and then checked it again. Code 34 seems to indicate that a circuit is either not grounded or shorted. Anyone have this issue?

Roy

RSLyrick · 5 Hours Ago

Hey Roy,

How's your little MAP vacuum hose : https://www.jerrysgaskets.com/hose-m...ew-90-95-13d4/ ?

Are you able to use an ALDL logger and follow the FSM diagnostic chart step by step for DTC 34 ?

Jetjock · 2 Hours Ago

I don't have a Tech 1 or anything like that. The vacuum hose looked good when I replaced the MAP sensor. Code 34 looks to be about a short or not being grounded. After running the engine, I will check the codes again. I'm using a paperclip to get the codes because the other way I did it was with some cartridges and they disappeared when I sold my 92 Z.

Roy

RSLyrick · 1 Hour Ago

I've never tested what I assume to be the cheaper alternative :

Moates ALDL cable : https://shop.moates.net/products/cab...aldl-connector
Moates Converter : https://shop.moates.net/products/ald...aldl-converter
TunerProRT : https://www.tunerpro.net/downloadApp.htm
ADS file for your 93 ZR-1.
A laptop.

You could get everything for 120$ but I've never tested this setup. Maybe other members can confirm that it works...

That would allow you to read the realtime MAP voltage value provided by the ECM itself when the car is running or just with ignition ON.

An open on the MAP signal wire and/or reference voltage will also trigger DTC 34, not only a short on the signal wire.

So be sure to check the MAP connector and ECM connector (RED one). A good test consist in wiggling the harness / connector around when the car is running and check for code 34 or engine reaction.

A soldering issue on the ECM could also prevent the MAP signal from reaching the ECM components from time to time. Same goes for the 5V voltage reference voltage but other systems use this reference as well (EGR, TPS...) so you would get other codes as well.

And about the MAP hose, don't assume it's good. Remove it, put a vacuum pump on one end, and block it with your finger on the other end and test how it holds.

1 Day Ago	#1
Jetjock Join Date: Mar 2008 Location: Auburn, KY Posts: 563	Code 34 on 93 LT5 Earlie, I had a code 33, 45 and 65. I changed out the MAP sensor, disconnected the battery, ran the engine and checked the codes again. This time, I got a code 34 and the other codes disappeared. I plan to run the car this afternoon and then checked it again. Code 34 seems to indicate that a circuit is either not grounded or shorted. Anyone have this issue? Roy __________________ Roy L. Carman If I feel the need for speed, I just think about flying the B-777. 1989 Dk Blue Coupe lost in divorce 1991 Black Coupe SOLD 1992 Black ZR-1 #423 SOLD! 1993 Ruby Red 40th Anniversary ZR-1 #334 1995 Black ZR-1 taken by ex-wife 2002 Pewter Coupe no idea where it is 2003 50th Anniversary Corvette #No idea what number SOLD! ZR-1 Net Registry #516 Grand Sport Lifetime Member NCM Lifetime #1468

5 Hours Ago	#2
RSLyrick Join Date: Oct 2023 Location: Germany Posts: 42	Re: Code 34 on 93 LT5 Hey Roy, How's your little MAP vacuum hose : https://www.jerrysgaskets.com/hose-m...ew-90-95-13d4/ ? Are you able to use an ALDL logger and follow the FSM diagnostic chart step by step for DTC 34 ?

2 Hours Ago	#3
Jetjock Join Date: Mar 2008 Location: Auburn, KY Posts: 563	Re: Code 34 on 93 LT5 I don't have a Tech 1 or anything like that. The vacuum hose looked good when I replaced the MAP sensor. Code 34 looks to be about a short or not being grounded. After running the engine, I will check the codes again. I'm using a paperclip to get the codes because the other way I did it was with some cartridges and they disappeared when I sold my 92 Z. Roy __________________ Roy L. Carman If I feel the need for speed, I just think about flying the B-777. 1989 Dk Blue Coupe lost in divorce 1991 Black Coupe SOLD 1992 Black ZR-1 #423 SOLD! 1993 Ruby Red 40th Anniversary ZR-1 #334 1995 Black ZR-1 taken by ex-wife 2002 Pewter Coupe no idea where it is 2003 50th Anniversary Corvette #No idea what number SOLD! ZR-1 Net Registry #516 Grand Sport Lifetime Member NCM Lifetime #1468

1 Hour Ago	#4
RSLyrick Join Date: Oct 2023 Location: Germany Posts: 42	Re: Code 34 on 93 LT5 I've never tested what I assume to be the cheaper alternative : Moates ALDL cable : https://shop.moates.net/products/cab...aldl-connector Moates Converter : https://shop.moates.net/products/ald...aldl-converter TunerProRT : https://www.tunerpro.net/downloadApp.htm ADS file for your 93 ZR-1. A laptop. You could get everything for 120$ but I've never tested this setup. Maybe other members can confirm that it works... That would allow you to read the realtime MAP voltage value provided by the ECM itself when the car is running or just with ignition ON. An open on the MAP signal wire and/or reference voltage will also trigger DTC 34, not only a short on the signal wire. So be sure to check the MAP connector and ECM connector (RED one). A good test consist in wiggling the harness / connector around when the car is running and check for code 34 or engine reaction. A soldering issue on the ECM could also prevent the MAP signal from reaching the ECM components from time to time. Same goes for the 5V voltage reference voltage but other systems use this reference as well (EGR, TPS...) so you would get other codes as well. And about the MAP hose, don't assume it's good. Remove it, put a vacuum pump on one end, and block it with your finger on the other end and test how it holds.