2004 Ram 1500
4.7 engine
273,530 miles

So here's what transpired. Surprisingly, with all the miles on the truck, she ain't lookin' too pretty these days (rusting up), but she sure runs good, that is, until this morning.

So, the last time I ran her, I was out for a few hours and the truck ran great as always. This morning I go to start the truck up and she starts right up, as always. But, I noticed [problem #1] the clock on the radio was wrong and the radio was making static noises and was on AM instead of FM. Very strange.

At first I thought someone had screwed around with the truck and somehow may have disconnected the battery so I shut the truck off and went under the hood. Battery was fine, cables were clean and on tight and the truck started right up again with no problem.

Went 5 minutes down the road to get gas and on the way back, the truck [problem #2] started missing, so I did the 2 tests turning the key and the other with the odometer button and here are the results.

P0300 code

C-Code A3 18

Now I know the P0300 is a multi-misfire and can be caused by various things, so I ordered an OBD2 scanner to see if it will give me a better readout.

A3 means there is a battery voltage open, but I'm not sure what that translates to.

The 18, well I can't find anything on that at all.

Oh, and one more thing. For the past couple years the CEL randomly comes on and goes off. I had it checked a few times by a couple different mechanics and was told not to worry about it, it's caused by the oxygen sensors. I did notice that it comes on [wait for it] the day before it rains and goes off the day after the rain stops, so I've been using it for keeping track of the weather. What can I tell ya?

In the mean time, any input on what direction I can take now before I get my scanner would be helpful. I need to try and find out what these codes mean, especially the A3 and 18 and get her back up and running. Thanks!

 

Decided to check the c-codes again (using the trip/odometer button) five times about a minute or so apart and each time I got a different code.

A3 24
A3 30
A3 32
A3 34
A3 36

Strangely enough, all these and the original c-code A3 18 have no explanation except A3 24 (Battery voltage open / Turn hazard switch input circuit shorted).

Thing is, all my lighting/blinkers, etc., all work on the truck.

 

Can you look at live data? I would be looking very carefully at the 02 sensor data...

 

The scan tool I ordered won't be in until the end of the week and I'm not sure if it does live data. I do know the 02 sensor is going bad, since it comes on the day before it rains and goes off the day after it rains.

I did find the following information on the c-codes and hopefully this will help others, as well as myself. "On c-codes, the first two digits are the fault code. The last two digits are the number of key cycles that have taken place since the fault took place." So with that said, then that would explain the second set of digits increasing every time I check the c-codes. That leaves me with looking at the first two digits "A3", which narrows down to having a "battery voltage open".

In the manual I have, this would mean either the "Front Control Module" is bad or the "Power Distribution Center" is bad. First, I'm going to clean up the wiring and nuts that attach the Power Distribution Center (fuse box) and see if that helps. I will update once this is completed.

 

You could definitely have your battery load tested and your charging system tested as well. Excessive ripple from the alternator can cause a ton of problems that would otherwise appear to have nothing to do with the charging system, and even a bad battery can do some pretty strange things.

I would start with the cheap stuff before chasing computer modules!

 

Checked the battery and it's at 12.75 and when started, it jumps to over 14 then works it's way down to just over 13.

 

Okay, so I finally got my OBDII Scanner in and ran some tests then reset the CEL just to start fresh. The CEL was off for a few days and the P0300 code was gone, but the c-code A3 still showed when testing directly from the dash.

All looked good until today when the CEL came back on, so I ran the full diagnostics with whatever the scanner could do and here are the results:

(Note: the scanner doesn't do c-codes, so I did that one again from the dash and still had the A3 code)

Powertrain Codes:

P0300 Random multi cylinder misfire (stored)
P0151 02 sensor current low voltage bank 2 sensor 1 (stored)
P0440 Evaporator emission system (pending)

Freeze Frame:

DTCFRZF P0300
FUEL SYSA CL
FUEL SYSB OL-DRIVE
LOAD_PCT (5) 66.3
ECT (*C) 37
SHRTFT 1 (5) -4.7
LONGFT 1 (5) 0
SHRTFT 2 -32.8
LONGFT 2 0
MAP (kPa) 65
RPM 260
VSS (km/h) 0
Spark Adv (*) 7
IAT (*C) 26
TP (%) 20.4
PTO_STAT off

I/M Readings:

DTC 2
MIS check
FUE check
CCM check
CAT check
HCAT pending
PdDTC 1
EVAP check
AIR pending
OS2 check
HRT check
EGR pending

Since DTCs Cleared:

MILL ON
MIS OK
FUEL OK
EVAP OK
CCM OK
CAT OK
HCAT N/A

Live Data:

DTC_CNT 2
FUEL SYSA CL
FUEL SYSB CL
LOAD PCT (%) 19.6 - 20 average
ECT 96
SHRTFT 1 -1.6 to 1.6 average
LONGFT 1 0
SHRTFT 2 -0.8 to 1.6 average
LONGFT 2 0
MAP (kpa) 30
RPM 600 average
VSS (km/h) 0
Spark ADV 10 to 12 average
IAT (*C) 28
TP (%) 12.2
O2SLOC B1S12 B2S12
O2S 11 (V) .76 to .78 +/-
SHRTFT 11 (%) -2.3 to -3.1 +
O2S 12 .685
SHRTFT 12 (%) 99.2
O2S 21 (V) .477 to .78 +/-
SHRTFT 21 (%) -2.3 to .8 +/-
O2S 22 (V) 99.2
SHRTFT 22 (%) (didn't get this one)
OBDS UP OBD II
PTO_STAT OFF
MIL_DIST (km) 78

 

SHRTFT 2 -32.8
LONGFT 2 0

These two make me wonder.... that's pullin' a LOT of fuel on bank 2.

 

Yeah, I'm trying to figure this out myself. Those readings were taken earlier today and then all of a sudden tonight my CEL goes off, so I'm going to recheck again, but not sure if I should first erase the codes, as the three P codes still show.

I did come across two good videos explaining all this, but finding it hard to wrap my head around all the information right now. According to the P codes, I should have a misfire, which I haven't noticed and a low voltage in B2 S1, but since the CEL is now off, but the scanner still shows the code, I may have to erase the codes (my first time using this scanner, so I'm not sure what to do here).

Here are the video links to look at:


Thought these were very interesting.

 

Yeah, clear the codes, and drive it for a while. See what happens. May have just been some crap in one of the O2 sensors.