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Discussion Starter #1
Hi
I am a 3rd owner on a 2.5L Dakota which has a 2" lift improperly done, with an electrical wiring nightmare, exhaust gasket leak and ball joints that are square joints. I am determined to see if I can save this truck with the little cash I have.
My major issue at the moment is the flashing headlight ECU problem. I have read that there is a resistor that could be the cause. I am soldering certified and have ESD equipment. My question is can I open the ECU and remove the PCB without special tools?
 

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Hi
I am a 3rd owner on a 2.5L Dakota
My major issue at the moment is the flashing headlight ECU problem. I have read that there is a resistor that could be the cause. I am soldering certified and have ESD equipment. My question is can I open the ECU and remove the PCB without special tools?
I wouldn't mess with the ECU (PCM) on your 98 without knowing how the
lights are connected. BTW..You didn't mention if the tranny is manual shift or automatic. If it's automatic, then probably it has a shift solenoid pack in it and controlled by what we call the PCM.

While the PCM can be taken apart, without a circuit board layout and
schematic drawing, you are just asking for trouble doing it, as
the 3 connectors that connect with it have NO HEADLAMP CIRCUIT
connecting pins to the ECU/PCM.

Besides, what makes you think it's the ECU controlling your headlights?

Generally the headlights are controlled by a headlamp switrch and a relay in the PDC

SYMPTOM: HEADLAMPS FLASH RANDOMLY
1. Poor lighting circuit ground. (Test for voltage drop across ground
locations.)
2. High resistance in headlamp circuit. ( Test amperage draw of headlamp circuit.) Should not exceed 30 amps.
3. Faulty headlamps switch circuit breaker.
Replace headlamp switch.
(Usually this is the most common cause.)
4. Loose or corroded terminals or splices in circuit.
( Inspect and repair all connectors and splices)


You really need to get a Haynes manual for the electrical diagram of the
exterior lighting for your truck. If your truck has fog lamps, there is
a fog lamp relay in the PDC as well that can interfere with the headlights
expecially when dimming the headlamps from high Beam to Low Beam.

Also, IF your truck is equipped with have the DRL (daytime running lamps there is a SEPARATE DRL MODULE that also AFFECTS the brightness of the headlights.

Finally, check the charging system to make sure the voltage across the
battery is consistently at 13.5 volts with the engine running. If the
voltage is fluctuating, it could be the Alternator, connections to the
alternator (including the ground connections) or possible the EVR..
electronic voltage regulator...which is in the ECU (PCM)...

but as suggested, you have a lot of other things to check out first
 

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Welcome to the Z from NC! ^^You've got great help there with Carverman, he knows these trucks. Good luck and enjoy the forum!
 

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Discussion Starter #4
thank you
The reason for the ECM was I had did a search, locating multiple people with the same problem, the most common fix for the flashing light after lights had been on for approx. 2 minutes was a ECU or as they called it the TCM had a resistor malfunction.
I have did the following. Replaced the multi-fuction switch, voltage output 13.9v, head lights with no fix but if I plug only 1 headlight in either 1 plugged in with the high on or off the flashing stops. But plug the 2nd in and with in 2 min. the head lights only flash
The grd is good but I have not chk'd while the problems is happening, I haver not replaced the pull switch for on and off.
Again thanks.
 

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Welcome to the Dakota Z Family from Southern Georgia!
Glad you decided to join us.
 

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thank you
The reason for the ECM was I had did a search, locating multiple people with the same problem, the most common fix for the flashing light after lights had been on for approx. 2 minutes was a ECU or as they called it the TCM had a resistor malfunction.
Ok, the "TCM" you may be referring to is known the CTM (Central Timer Module) on the Dodge Dakota, which is responsible for timing functions, such as wiper delay, keyless entry,etc, and on some models where headlights being left on by accident, the lights are turned off after a some length of time to prevent battery discharge.

This is considered a Body Module and is NOT the Engine/Transmission control
computer or PCM (Powertrain Control Module).

The CTM is located inside the cab, usually under one kick panel near the
passenger side..or driver's side, depending on the model of truck.

I have did the following. Replaced the multi-fuction switch, voltage output 13.9v, head lights with no fix but if I plug only 1 headlight in either 1 plugged in with the high on or off the flashing stops. But plug the 2nd in and with in 2 min. the head lights only flash
The grd is good but I have not chk'd while the problems is happening, I haver not replaced the pull switch for on and off.
Again thanks.
These are the standard headlamp bulbs and not LED or some aftermarket
ones you've added, I presume?


If I remember correctly, we ran into a similar problem before on this forum
and we discussed it in length. The CTM was controlling the headlights
and one headlight wasn't coming on. The CTM output that drives both
headlights (separately) was faulty and in the end, he used a relay hooked
up to supply power to the headlights using the remaing good CTM output
to drive the relay coil.

I'll look for it, it was a few months ago.
 
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