Jaime
Dodge Dakota
JOIN HERE
7/27/2014
23:09:51
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 Subject: Dakota No Bus Message
IP: Logged
Message:
I've looked around on many sites and Googled it every way I
could think of, but I haven't been able to find an answer for my
question. I have a 2004 Dodge Dakota, quad cab, 4x4 and
automatic transmission with around 210,000 miles on it. In the
last year or so, I started having intermittent electrical/computer
problems.....I get the NO BUS message in the odometer, all
the idiot lights, no fuel gauge and the truck won't start.
Previously, leaving it sit until the next day and trying again has
temporarily resolved the problem. It has been very intermittent,
last happening back in mid-May, but struck again 3 weeks ago
and hasn't been as cooperative as before. After a week, it
finally started up....I drove it to work that Friday, checked it on
Saturday and it started, but tried again Sunday evening and it
was a no go. It hasn't started again since then, which was 2
weeks ago. I have done the step by step testing of the 5V
buses to the various sensors powered from the PCM, but I
have no 5V being output from the PCM. If I put 5V in from an
external source, the sensors all get the voltage, but I still have
the same condition. Therefore, I was curious to what was
going on with the input voltage to the PCM, which from what I
can tell from my wiring diagrams, is on pin 29 (RD/WT) of the
C1 connector at the PCM. I only get around 2.5V at that pin
with it disconnected from the PCM. I went to the other end of
it, inside the PDC at C106. When I unplug the connector and
test pin 12, I get a little over 12V, which is what I would expect.
I tested the resistance between C106 pin 12 and the C1 pin 29
and the resistance is nothing (maybe 1-2 ohms). I also
checked C106 pin 12 for a short to ground and that reads as
open. Then, when I reconnect the C106 connector in the PDC,
but leave the C1 PCM connector disconnected and probe the
back of C106, I again get only around 2.5V. I feel like I'm
starting to lose my mind.....from what I can tell from the wiring
diagram, I should be getting the full 12V at the C1 pin 29/C106
pin 12. I have verified all but 3 ground points buried up under
the dash. Does anyone have any idea what is going on here
or if I'm missing something in the wiring diagram and this is
correct? I have ordered a remanufactured PCM, but I want to
figure out what is going on with this before I dare plug in a new
PCM. Any help/suggestions would be greatly appreciated. I
have tried unplugging the crankshaft position, camshaft
position, TPS and MAP sensors hoping that it was still
something with one of them causing problems.
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