Solved Do GEM DTC codes persist through battery disconnect?

[usapadyra]

I just started using FORScan with a bluetooth adaptor.

Previously I have only ever observed OBD codes relating to the CEL, using either a cheapo OBD scanner or the check service at auto parts stores.

Usually in the process of troubleshooting, I'll use the battery disconnect method to clear the CEL when needed.

FORScan shows a few codes in the 'GEM' section which I have never seen before - presumably because basic scanners + Autozone don't read these.

Are codes from the GEM the kind that will not clear from a battery disconnect?

Last year I had a couple of things happen that I think could have set them, but after those things, I ended up leaving the car in storage with the battery disconnected for 5 months.

Ultimately I'm trying to figure out 'when' these codes could be from.

Are they safe to clear so I can see if they come back? The only one I'm concerned about is the Vehicle Speed Sensor (P0500), but I think this can be explained from when my alternator died while driving and the tachometer and speedo both stopped working.

If my speedo has worked flawlessly for thousands of miles over many months, can I safely assume that the VSS is in working order? Transmission also shifts fine.

Thanks

 

[Pete Deering]

I just started using FORScan with a bluetooth adaptor.

Previously I have only ever observed OBD codes relating to the CEL, using either a cheapo OBD scanner or the check service at auto parts stores.

Usually in the process of troubleshooting, I'll use the battery disconnect method to clear the CEL when needed.

FORScan shows a few codes in the 'GEM' section which I have never seen before - presumably because basic scanners + Autozone don't read these.

Are codes from the GEM the kind that will not clear from a battery disconnect?

Last year I had a couple of things happen that I think could have set them, but after those things, I ended up leaving the car in storage with the battery disconnected for 5 months.

Ultimately I'm trying to figure out 'when' these codes could be from.

Are they safe to clear so I can see if they come back? The only one I'm concerned about is the Vehicle Speed Sensor (P0500), but I think this can be explained from when my alternator died while driving and the tachometer and speedo both stopped working.

If my speedo has worked flawlessly for thousands of miles over many months, can I safely assume that the VSS is in working order? Transmission also shifts fine.

Thanks

View attachment 450118

The GEM codes will not clear , because they are hard codes.
When the VSS sensor fail, the tachometer and speedo both stopped working. You should also experience transmission shift problems. The controller does not know how fast you are going, so it can't shift at the right speed.
Did someone disable the anti thief system. Pull the fuse and or relays?
B1398, and B1302 will be there till you fix. It could be a fuse?
Hood switch circuits and RAP and P1260 separate issue.
It could be a fuse?
B1318- charge your battery.? What is the BAT voltage, measure it. If the voltage is low it will always be low, till you address it.

 

[usapadyra]

The GEM codes will not clear , because they are hard codes.
When the VSS sensor fail, the tachometer and speedo both stopped working. You should also experience transmission shift problems. The controller does not know how fast you are going, so it can't shift at the right speed.
Did someone disable the anti thief system. Pull the fuse and or relays?
B1398, and B1302 will be there till you fix. It could be a fuse?
Hood switch circuits and RAP and P1260 separate issue.
It could be a fuse?
B1318- charge your battery.? What is the BAT voltage, measure it. If the voltage is low it will always be low, till you address it.

Thanks for the input. I believe the VSS sensor code was set when my alternator failed while driving (both tach and speedo stopped working). But I got the alternator and battery replaced 9000 miles ago and the tachometer, speedo and transmission have worked flawlessly since.

The other GEM codes were most likely set because of an issue I was having with the GEM, which I have also since fixed - see here if interested:

***Solved*** No power windows / dome lights / wipers / rear defrost

So, sadly, I have to carry on with this. The problem returned after a long time (2 weeks) sitting in the rain that came over NorCal. The issue also first occurred sitting parked in the rain, and resolved after going for a drive in the dry. This time, again, the issue resolved entirely after...

www.explorerforum.com

As you said, the codes did not clear with a battery disconnect. For some reason it didn't occur to me to just disconnect the battery and try. I ended up clearing them using FORScan. We'll see if they come back. I suspect not.

 

[J_C]

When I first started having an ABS sensor problem (that turned out to be another bad hub), I pulled the ABS module fuse, which caused a VSS code. Once the fuse was put back in, it did not clear by disconnecting the battery, so was cleared with a scan tool.