Shouldn't disconnecting batteries clear the P Codes?

[Crunch]

Yesterday I was running some quick errands and noticed the Check Engine light on. I pulled over, shut off the engine and called up the codes to see what was happening. I had the dreaded P2121 code, which is the APPS response and efficiency. I continued with my errands without problem, and parked the truck for the night. The Check Engine light was on till I parked the truck. This morning I disconnected the positive cables on both batteries for about an hour. My clock needed to be reset, but my radio stations were still programmed correctly. The Check Engine light was gone, but the P2121 code hadn't cleared. I was under the impression that disconnecting the batteries would clear the codes. Is this not correct? The APPS has been replaced twice, and it runs close to $700 a pop. I'm hoping this is just a glitch, and the APPS is working fine. Even when it was acting up it was only an intermittent problem, but I'm on the road a lot this time of year and this isn't the kind of problem that is good to have when away from home.

 

[cerberusiam]

No, not if it is a hard DTC. The CEL will go off after so many restarts but the codes stay stored until cleared. If you clear the code and it comes right back APPS is still bad.

Why are you paying $700 when a the fix is only $165-170 delivered? The Timbo APPS replacement for the engine mounted sensor is too cheap and effective to pass up. Genos carries them so order one up and go thru your harness also. A lot of the APPS problems are harness related. If you have the one under the battery tray that is also usually a harness issue. Timbo has some good info on how to track the problems down on his site.

 

[Crunch]

No, not if it is a hard DTC. The CEL will go off after so many restarts but the codes stay stored until cleared. If you clear the code and it comes right back APPS is still bad.

Thanks, that's good to know.

Why are you paying $700 when a the fix is only $165-170 delivered? The Timbo APPS replacement for the engine mounted sensor is too cheap and effective to pass up. Genos carries them so order one up and go thru your harness also. A lot of the APPS problems are harness related. If you have the one under the battery tray that is also usually a harness issue. Timbo has some good info on how to track the problems down on his site.

I've never had any experience with a throttle that uses an APPS, so it is completely alien to me. I looked at the TIMBO information at Geno's, and also downloaded the instructions and watched the video. Looks pretty straight forward, so I may go that route after all. I'm not sure where the APPS harness is located for my truck, but I have a memory of someone telling me it is between the engine and the firewall. But that is just a vague memory so I don't know for sure. But I don't have an exhaust brake, and according to Geno's, at long as the harness is not under the driver's side battery the TIMBO should work.

Thanks!

 

[cerberusiam]

APPS harness depends on the location of the APPS. Generally, on all auto trucks it is on the left front of the engine. Manual trucks, under the driver side battery. The exceptions are manuals with an engine mounted APPS. At the age of the truck, connectors and any sharp bends on the harness are suspect for connection quality.

 

[Crunch]

APPS harness depends on the location of the APPS. Generally, on all auto trucks it is on the left front of the engine. Manual trucks, under the driver side battery. The exceptions are manuals with an engine mounted APPS. At the age of the truck, connectors and any sharp bends on the harness are suspect for connection quality.

After watching both the calibration video linked to by Geno's page, and another video showing the actual replacement of the APPS I will definitely do this myself the next time it fails, and purchase the TIMBO from Geno's, as well. Thanks for providing this information!

 

[cerberusiam]

That is the one they have done right on the late 3rd gen and 4th gen trucks if FIX the blasted APPS\TPS that were so prevalent in 1st and 2nd gen trucks. Most of any existing issue are self-induced in the newer trucks. Glad I could point you in a positive direction.