Probably a stupid question did the alternator a/c test on my truck reads around .032 say there and watched it for a minute and it shoots up to .09-.1 for about 5 seconds than returns to .032. Does the same cycle like clock work. I’m assuming it is the alternator full fielding? 

Yes, you grid heaters are hitting. 

 

I would say the diodes are OK but I would do the W-T ground mod. On a grid heater hit I'm barely 29mV AC and idle no load is now about 12mV AC.

 

 

I will do that for good measure I appreciate the quick response and input. I’m chasing an intermittent dead pedal. I have a fass lift pump and a reman vp that was supposed to be less than a year old when I bought truck a year ago. I have done every test I can think of and everything passes. But with how sporadic the issue is I would expect everything to pass. I’m leaning towards an apps at this point but not throwing any codes. I’m not a throw parts at things kind of guy.

Most dead pedal issues are usually not the APPS sensor. The last bout I went thru was the 5v reference signal wire. 

Interesting. We talking voltage drop from a broken/corroded wire between ecm and apps? Or bad ecm?

I would think a bad reference wire would throw a code. I could see how a dead spot in the potentiometer in the apps could cause the pedal to go dead without throwing a code

 

Edited November 29, 20186 yr by 69superbee440

Get you wireing cleaned up first with the WT mod and just all grounds in general, then you'll need some sort of life tool to see what apps does when you're driving down the road and it acts up. The 5v loop is just that, it's not 12v dropping that low, it is an actual 5 volt circuit that some sensors run on and when it malfunctions from a bad connection it causes random problems. 

I was speaking of the 5v reference loop for the sensors that @Dieselfuture speaks of . I cut mine many years ago on the advise of someone I thought was smarter than me. That splice worked it way loose and caused several gremlins to raise their head. Dead pedal was part of it. By dead pedal I dont mean a dead spot thru the range of the accelerator pedal but rather the engine going to idle while under load with no response no matter how much you push the pedal. I did get APPS sensor codes during these issues but changing the APPS never fixed them.

 A dead spot in the pedal that you can push pedal more and get thru the dead spot is definitely an APPS issue.

If you do decide that you need a new APPS then get a Timbos.  It's easy to change out and set up and the best thing is they're for sale in the forum store.  

Cleaned up ground on left front fender under battery was pretty crispy. So far so good ? was acting up pretty consistent so we will see what happens. I just installed a edge juice so can monitor the apps if it does act up again. Now if I could just solve my abs issue!

Master ground for the big 3 computers (PCM, ECM, and VP44) is the passenger side battery cable. 

 

As for W-T that would drop the AC noise for sure. As for the APPS sensor just monitor the value for sudden drops when it acts up or sudden 100%. Either way it will trip a P0121, P0122 or P0123 codes. 

 

The only other device that will dead pedal is the VP44. Again this needs the W-T ground mod for protection.