Wednesday, January 29, 2025

Battery Keeps Going Down Update

The 2013 Silverado testing showed good battery, alternator and no excessive draw so I had decided to look at a full scan for clues.

The ground at G302 looked like a good place to inspect after I monitored the voltage at the passenger presence module and found it to be dropping to 8 volts during a crank. Looking under the passenger seat I found several loose tools stored there. The socket set was in a case but screwdrivers and crescent wrenches all were laid loosely. Both screwdrivers had worn into the wire harness. I removed the tools and placed them in bag. I put the tools in the passenger rear floor (extended cab). I cleared the codes and monitored the voltage for several starts and now the drop was to 10.5 volts during cranking which should be fine. I did not access the ground which would require seat removal as it seems fine now. No codes have reset.

Now did the "fix" address the battery complaint? I don't know. It will be a wait and see but I do seem to have taken care of the problem I did find.

Kenny@GGAuto.Repair

Tuesday, January 28, 2025

"Battery Keeps Going Down"

I had three of these "battery loses power" jobs to look at today. I enjoy electrical work. It usually can be done in a logical process vs mechanical problems which can be anything. <grin> Typically on an electrical system diagnosis you will start at the battery. You need a good and fully charged battery for tests to be relevant. It isn't good enough to just assume it is fine. You test. I like to test the battery by first disconnecting it from the questionable system so that there is no interference. Before disconnecting the battery on the 2002 Avalanche I connected a memory saver to the system which is a sort of portable auxillary battery that will keep the truck's system memories intact while I test the battery.

The battery was good but would need a full charge. I like to use low amperage and slow charging because it is the most stable and reliable but it does take a few hours.

Once the battery was fully charged and cables reconnected, I removed the memory saver. Because the truck system never lost a power source I didn't have to wait for the system to enter sleep mode, it was already there. I could immediately test both the main circuits feeding from the ground side and found current draw well within acceptable range.

I also found the alternator to be working properly.

So, the battery was good, alternator good and no excessive draw on the battery. What was the problem? When I was disconnecting the battery terminals I had noticed the ground cable was not fully tight and it would not tighten when I did try the bolt. I went ahead and disconnected for the testing but once I was reconnecting the battery I could see the ground bolt was stripped. A new bolt tightened fully and I had a good connection. So what I found bad was a ground terminal connection at the battery due to a stripped bolt.

Next up was the 2001 Crown Vic. The battery was completely drained on it and it was a new battery. I had to disconnect the battery from the car to even get it to begin charging so I knew this one had excessive draw. Once I was able to test current draw on this one, I could see why the battery was dead.

Instead of starting by isolating circuits I thought that just might be something I could see on, like a trunk light or glove box light or something. I noticed a glow inside and there was something connected to the power outlet inside the car and the connector led was lit up. It was an aftermarket seat warmer on the passenger seat. The switch of the warmer had 3 settings but all were drawing power. I disconnected the warmer and all was good.

Now the 2013 Silverado battery was up to 90% so didn't take long to reach full charge. Alternator tests good and all three of the main circuit feeds from positive post have draw within specs.

Not sure what I'll find there but at least gonna let it sit overnight. It isn't unheard of for a computer to suddenly wake up on occasion and turn a few things on that shouldn't be. Gonna do a full system scan for clues and see what it does overnight.

Kenny@GGAuto.Repair

Thursday, October 17, 2024

2002 F150 with Lean codes 4.2

I was going through some old files and this one was easily diagnosed from just the paperwork though the truck left here years ago. 2002 Ford F-150 XL with 4.2 engine and trouble codes stored that indicate lean fuel mixture on both banks.

Important clues are stored in the freeze-frame. The truck is sitting at idle, still warming a cold engine and fuel trims are high.

These engines had a known problem with the seals around the bolts that attach the plenum to the lower intake manifold. While the engine was cold the seals would draw up and allow a vacuum leak. Once warmed up the seals would stop leaking. This is a common problem on many engines with the plenum gaskets allowing this to happen but on the 4.2 it was usually not the actual plenum gasket but the seal at the attaching bolts. The fix was to replace the plenum gasket and attaching bolts. The gasket was readily available at any parts store but to get the updated bolts they had to come from Ford. The updated version was green in color.

You could verify this as the problem by letting the vehicle cool down overnight, start the engine, pull up the short term fuel trims on a scan tool and watch the data while spraying some carb cleaner in the area between the plenum and lower intake. If the vacuum leak was there it would pull in some of the carb spray and you would see the immediate change in the fuel trim.

Kenny@ggauto.repair