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Hi everyone,

I have a 1994 Dakota 4x4 regular cab (I've owned it since new) that started acting up just recently. The other day driving at 50 mph, the engine backfired and quit and, at the very same time, smoke came out of the heater vents with electrical fire smell (ozone). Engine wouldn't start for about 45 minutes, then when it did, I had all sorts of weird things happen:
- speedo stopped working
- tach works sometimes, when it works, the horn also works; when the tach doesn't work, then the horn doesn't work either.
- oil pressure, voltmeter, fuel gauge, temp gauge all work fine.
- idiot lights come on when the ignition switch is first turned on and then turn off like they are supposed to.
- dash lights don't work
- dome light doesn't work
- heater fan doesn't work on any setting
- headlights stay on with the headlight switch off and the key out of the ignition (ran my battery down after parking it over night), the only way to turn off the lights is to pull the 50amp fuse in the Power Distribution Center
-backup lights don't work
- #13 fuse is good, but there is no power to either side of the fuse.

Thanks for your help!

Joe.
 

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Dakota Electrical Gremlins

Joe,

I'm having very similar issues with my Dad's Dakota. Did you ever find a solution to your issues?
 

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. The other day driving at 50 mph, the engine backfired and quit and, at the very same time, smoke came out of the heater vents with electrical fire smell (ozone). Engine wouldn't start for about 45 minutes, then when it did, I had all sorts of weird things happen:
Sounds like you had a serious short or overcurrent condition in your
blower circuit?.. for smoke and a burning wire smell to come out of
the blower vents?

Hmm? where to begin on this tough electrical problem.

I am going here by the wiring diagram from my Haynes manual for my 1998 Dakota Magnum V8.
BTW, You should be using a Haynes or wiring diagram for your 1994, but I expect that the wiring will be the same in most cases as with my '98.

- speedo stopped working
- tach works sometimes, when it works, the horn also works; when the tach doesn't work, then the horn doesn't work either.
Speedo/tach controlled by PCM through the instrument cluster controller.
Sensors used for tach is different from sensor for speedo, so doubt
it's anything to do with sensors or PCM.

- oil pressure, voltmeter, fuel gauge, temp gauge all work fine.
- idiot lights come on when the ignition switch is first turned on and then turn off like they are supposed to.
instrument cluster controller is working then

- dash lights don't work
- dome light doesn't work
Dash lights on instrument panel are controlled by a 5a fuse in junction block (the driver's side fuse access panel) which goes to the headlamp
switch rheostat dimmer from the headlamp switch witch goes over to
the cluster controller as a "dim setting". A seperate fuse 5A
in the junction block fed through joint connector #4 feeds +12v to
the dashboard controls lighting.

Dome light is controlled from the Headlamp switch getting it's ground
from G200 in joint connector #4. This goes to the junction block
and joint connector #4 which has a separate 10a fuse in the junction
block.

- heater fan doesn't work on any setting
Blower is controlled by by a 40amp fuse in the PDC going through the
contacts of the blower relay (big black square relay) located in the PDC.
This supplies 12v battery to one side of the blower motor.

The ground side of the blower motor goes to the blower speed resistor block which would be located inside the dash and close to where
the blower motor is, (as the air movement in the vents needs to cool the
resistor block). The resistor block is connected to the heater/a/c control
which gets it ground from G202.
Illumination for the blower/heater/ac settings comes from a 5amp fuse in
the junction block via joint connector #4.

- headlights stay on with the headlight switch off and the key out of the ignition (ran my battery down after parking it over night), the only way to turn off the lights is to pull the 50amp fuse in the Power Distribution Center
Headlamps are controlled by a 40amp fuse in PDC which goes then to
the headlamp switch via a thermal cutout in the switch and feeds the
multifunction (steering column stalk) switch which provides:

flash to pass, high beam and low beam capabilty.

Fog lamp switch gets 12v from a 15a fuse in junction block which goes
to the headlamp switch first, then another 5amp fuse in the junction block
and through joint connector #4 which also provides ground (G200) to
the headlamp switch which provides ground to the dome light.

-backup lights don't work
Backup lights are controlled by a 15amp fuse (from RUN ignition circuit)
to a daytime running lamp module and backup lamp switch via joint connector #1 in the PDC which feeds 12v to both backup lights.
Backup lights get their ground from G103.

- #13 fuse is good, but there is no power to either side of the fuse.
which fuse is "#13"? Is this one in the PDC or the junction block (fuse
panel)?

With so many functions not working after the engine died and a smell
came out of the blower vents, it's hard to start at a point to determine
the cause and the general area that it might have occurred.
Obviousl the first place to start is to check the fusing in the PDC
and the joint connector (fuse panel on side of driver's instrument panel) for signs of blown fuses.

If no blown fuses are uncovered to indicate which circuit(s) suffered
an overload or short, then it's going to bit a bit more difficult to trace.

The common areas between all of these circuits above is:
-any "major" blown fuse in either the PDC or the junction block (fuse panel)
- a possible short between 12v power feeds and grounds in joint connector #4
- a possible short between power and ground in the junction block
- fried resistor block to the blower..although this would only affect the blower
circuit and not all of the other functions you mention.

The best place to start unravelling the cause of this electrical mess, is to
start at the PDC and work back. I can't give any more specific information
until I get more specific answer on where the +12v power is missing.

Obviously if the engine died on you, then you have a serious short in the
PDC or junction block area (or a headlamp switch) that would affect the
run or start/runbcircuit that provides +12v to the ASD (autoshutdown relay)
which provides battery (via a 30amp fuse) to the PCM. The ASD relay
is fused in the junction block as well.
 
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