Need Help Trying to Understand How VSS/ECM Works - P0507 Code
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Teching In
Joined: May 2013
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From: FM, Texas
Need Help Trying to Understand How VSS/ECM Works - P0507 Code It has been suggested I post this here for comments. I have a GMPP LS3 crate motor with the GMPP E67 controller and harness installed in a 69 Camaro. I keep getting an intermittent P0507 Idle Speed High code. To help me troubleshoot the issue I was monitoring it with HPTuners and discovered that the engine controller loses the VSS signal and when I am running at speed I get the P0507 code. What is strange is that my electronic Autometer Speedo still works great. I have rechecked the wiring and confirmed I have the VSS connected to connector C3 pins 66 and 67 and the Speedo is connected through the bulkhead connector pin D as per the instructions. I do not understand how this works because I thought the controller passed the signal on to be used by the speedo. So how come the speedo works great and the controller loses the signal? I need the speed in the controller to be consistent for the reverse inhibit feature because it is darn scary to shift at 70mph and it goes into reverse instead of 5th. Would really appreciate some help on this.
TECH Fanatic
Joined: May 2010
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From: Atlanta, Ga
The P0507 DTC is high engine speed, not vehicle speed. What does your tach register? Take a look at this as well. http://hsv-gts.ls2.com/0506GTODTC/DTC%20P0507pdf.pdf
TECH Addict
Joined: Aug 2005
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From: Monroe,NY
The P0507 DTC is high engine speed, not vehicle speed. What does your tach register? Take a look at this as well. http://hsv-gts.ls2.com/0506GTODTC/DTC%20P0507pdf.pdf
He is trying to figure out why he loses speedometer reading.
Thread Starter
Teching In
Joined: May 2013
Posts: 23
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From: FM, Texas
Thanks for the input. This is all good information. I originally thought I had two separate problems to solve - reverse inhibit working intermittently and a CEL for high idle speed. Could not figure out what was going on so started continually monitoring with HPTuners and there seems to be a relationship between losing the speedo to the ECM, losing the reverse inhibit, and then the CEL for the high idle. The autometer tach and speedo continue to work great during these episodes. So I am back to trying to understand how the ECM handles the speedo signal from the VSS? How can the ECM lose the signal but the speedo still work? I really appreciate the help. Thanks
TECH Fanatic
Joined: May 2010
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From: Atlanta, Ga
I would suggest unhooking the tach and speedo and leave the HPT connected to the OBD port log the data and see if the DTC returns. I see CAN-BUS not connecting with my dash every once in a while on startup. Everything seems to run and drive just fine in these instances. I am not really sure what causes the issue.
