Need help with a couple DTC Codes..
Thread Starter
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
Need help with a couple DTC Codes..
I pulled my codes last night after observing the SES light illuminate after a long drive.. I got the following codes:
Module 1 - H72 & H74
Module 4 - H28 & H32
Ive searched around and found conflicting definitions for these codes..
Based on this;
http://tech.corvettecentral.com/2011...trouble-codes/
My codes are as follows:
DTC 72 – Vehicle Speed Sensor Loss
DTC 74 – Traction Control System (TCS) Circuit Low
DTC 32 – Exhaust Gas Recirculation (EGR)
DTC 28 – Transmission Range (TA) Pressure Switch Assembly Fault
Is this accurate?
& if so, I am a little confused because the car is a M6, 1993 LT1. It seems like Vehicle Speed Sensor and Transmission Range (TA) Pressure Switch Assembly are components of automatic transmission cars?
74 & 32 seem straight forward, but I am a little confused with 72 & 28.
Anyone have any experience with these codes, or be able to tell me if I am correct in my interpretation of my codes?
Module 1 - H72 & H74
Module 4 - H28 & H32
Ive searched around and found conflicting definitions for these codes..
Based on this;
http://tech.corvettecentral.com/2011...trouble-codes/
My codes are as follows:
DTC 72 – Vehicle Speed Sensor Loss
DTC 74 – Traction Control System (TCS) Circuit Low
DTC 32 – Exhaust Gas Recirculation (EGR)
DTC 28 – Transmission Range (TA) Pressure Switch Assembly Fault
Is this accurate?
& if so, I am a little confused because the car is a M6, 1993 LT1. It seems like Vehicle Speed Sensor and Transmission Range (TA) Pressure Switch Assembly are components of automatic transmission cars?
74 & 32 seem straight forward, but I am a little confused with 72 & 28.
Anyone have any experience with these codes, or be able to tell me if I am correct in my interpretation of my codes?
Melting Slicks
Joined: Mar 2008
Posts: 2,351
Likes: 222
From: Delta B.C. Canada
2023 C7 of the Year Finalist - Unmodified
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I pulled my codes last night after observing the SES light illuminate after a long drive.. I got the following codes:
Module 1 - H72 & H74
Module 4 - H28 & H32
Ive searched around and found conflicting definitions for these codes..
Based on this;
http://tech.corvettecentral.com/2011...trouble-codes/
My codes are as follows:
DTC 72 – Vehicle Speed Sensor Loss
DTC 74 – Traction Control System (TCS) Circuit Low
DTC 32 – Exhaust Gas Recirculation (EGR)
DTC 28 – Transmission Range (TA) Pressure Switch Assembly Fault
Is this accurate?
& if so, I am a little confused because the car is a M6, 1993 LT1. It seems like Vehicle Speed Sensor and Transmission Range (TA) Pressure Switch Assembly are components of automatic transmission cars?
74 & 32 seem straight forward, but I am a little confused with 72 & 28.
Anyone have any experience with these codes, or be able to tell me if I am correct in my interpretation of my codes?
Module 1 - H72 & H74
Module 4 - H28 & H32
Ive searched around and found conflicting definitions for these codes..
Based on this;
http://tech.corvettecentral.com/2011...trouble-codes/
My codes are as follows:
DTC 72 – Vehicle Speed Sensor Loss
DTC 74 – Traction Control System (TCS) Circuit Low
DTC 32 – Exhaust Gas Recirculation (EGR)
DTC 28 – Transmission Range (TA) Pressure Switch Assembly Fault
Is this accurate?
& if so, I am a little confused because the car is a M6, 1993 LT1. It seems like Vehicle Speed Sensor and Transmission Range (TA) Pressure Switch Assembly are components of automatic transmission cars?
74 & 32 seem straight forward, but I am a little confused with 72 & 28.
Anyone have any experience with these codes, or be able to tell me if I am correct in my interpretation of my codes?
Assuming that the 1993 is the same as the 1992, the code descriptions from my 1992 FSM are:
28 ECM detected the wrong potential voltage at the #3 quad-driver module circuit for 3 seconds.
32 EGR open command did not change the fuel mixture when the command was given during off idle operation. EGR opening should cause the mixture to be slightly richer because of the low oxygen content of the exhaust gas.
72 2nd or 3rd gear switch was open for 1.5 seconds when vehicle speed was above 30 MPH with engine speed greater than 5000 RPM and a throttle angle (TPS) above 70%.
74 EBCM operating voltage falls below 9.0
Thread Starter
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
Assuming that the 1993 is the same as the 1992, the code descriptions from my 1992 FSM are:
28 ECM detected the wrong potential voltage at the #3 quad-driver module circuit for 3 seconds.
32 EGR open command did not change the fuel mixture when the command was given during off idle operation. EGR opening should cause the mixture to be slightly richer because of the low oxygen content of the exhaust gas.
72 2nd or 3rd gear switch was open for 1.5 seconds when vehicle speed was above 30 MPH with engine speed greater than 5000 RPM and a throttle angle (TPS) above 70%.
74 EBCM operating voltage falls below 9.0
28 ECM detected the wrong potential voltage at the #3 quad-driver module circuit for 3 seconds.
32 EGR open command did not change the fuel mixture when the command was given during off idle operation. EGR opening should cause the mixture to be slightly richer because of the low oxygen content of the exhaust gas.
72 2nd or 3rd gear switch was open for 1.5 seconds when vehicle speed was above 30 MPH with engine speed greater than 5000 RPM and a throttle angle (TPS) above 70%.
74 EBCM operating voltage falls below 9.0
Now on to figuring out what the hell is needed to address 28, 72 and 74..
Instructor
Joined: Jun 2014
Posts: 152
Likes: 1
From: Ponce de Leon FL
Here's a great place to start!!
http://www.ebay.com/itm/1993-CHEVROLET-CORVETTE-SHOP-SERVICE-MANUAL-set-2-UsedLowPrice-/251929897812?hash=item3aa8312b54&vxp=mtr
Team Owner
Joined: Sep 2003
Posts: 25,389
Likes: 2,741
The 72 and 74 in earlier cars was common CCM error when an after-market radio had been added. Is your radio OE? I'm betting NOT. Those codes are discussed in the link you provided. I believe the 28 is usually an AC Clutch issue or cooling fan.
Last edited by WVZR-1; Apr 25, 2015 at 08:19 PM.
Thread Starter
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
Im going to replace my radiator because its leaking, but while i am in there I am going to do the water pump. When Im doing that im going to replace the spark plug wires and spark plugs as well.
After some thought, Im beginning to think that 28 & 32 are related. And that the EGR not operating well can cause some issues in the lower RPM range.
Thread Starter
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
The codes you pulled are all HISTORY codes or so you mentioned. I'd clear all of the codes and do it again using an appropriate scanner for detection of CURRENT DTC's. What drivability issue are you having?
The 72 and 74 in earlier cars was common CCM error when an after-market radio had been added. Is your radio OE? I'm betting NOT. Those codes are discussed in the link you provided. I believe the 28 is usually an AC Clutch issue or cooling fan.
The 72 and 74 in earlier cars was common CCM error when an after-market radio had been added. Is your radio OE? I'm betting NOT. Those codes are discussed in the link you provided. I believe the 28 is usually an AC Clutch issue or cooling fan.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I have found that this source for code explanations is most accurate and does a better job of breaking down the codes by year:
http://forums.corvetteforum.com/1576116036-post35.html
http://forums.corvetteforum.com/1576116036-post35.html
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