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Tim Mohr
Tim Mohr, ASE MASTER TECH
Category: Dodge
Satisfied Customers: 15121
Experience:  30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
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Changed the engine from a 03 durango to a 04 dakota 4.7

Customer Question

Changed the engine from a 03 durango to a 04 dakota 4.7 obviously it ran fine on the durango bit the harness is different so ised original harness and ecm now the truck wont crank no spark on the coils
JA: Have you checked the fuel supply? And are all the spark plugs working?
Customer: Fuel is fine no spark on any coil
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes checked grounds and plugs on connect and wires
JA: Anything else you think the mechanic should know?
Customer: I have to jump start it
Submitted: 3 months ago.
Category: Dodge
Expert:  Juan Crespo replied 3 months ago.

Hi there.

To clarify; the PCM is the original one for the Dakota, correct? Plus, the engine cranks but won't start because of no spark, so are fuel pressure and injector pulse OK? If no injector pulse, do you have access to a scanner that can read cam and crank sensor signals?

What do you mean you have to jump start it?

Customer: replied 3 months ago.
Correct battery wont hold charge so have to jump it to turn fuel is good no spark
Expert:  Juan Crespo replied 3 months ago.

OK. Usually when there is no spark, injector pulse is also absent, so to clarify this piece of crucial information, when you state "fuel is good" does that mean you have confirmed the PCM is indeed pulsing the injectors? Also, do you have access to a scan tool that can display cam and crank sensor data?

Expert:  Juan Crespo replied 3 months ago.

One more thing, the anti-theft system will activate if it sees low voltage from the battery. Are you keeping the charger on at all times?

Customer: replied 3 months ago.
Sucurity light flashes after a few attemps to start no scan tool fuel is flowing can smell it after a few times of trying to start it
Customer: replied 3 months ago.
Battery wont hold charge have to keep the jumper cables on at all times
Expert:  Juan Crespo replied 3 months ago.

I'm sorry but it looks like I won't be able to help you. I'll opt out so others may try. Please do not reply until another expert responds or the site will cycle the request back to me.

Expert:  Tim Mohr replied 3 months ago.

Hi, my name is ***** ***** the antitheft light on the dash is flashing? when you try to start it?

Customer: replied 3 months ago.
Only when i let go of the key to while trying to crank original ecm has 4 conectors the one from the durango had 3 thats why i dindt use the replacement engine harness
Expert:  Tim Mohr replied 3 months ago.

ok, the light flashing when you release the key after cranking, is caused by the computer not recognizing the signal from the key, this can happen if the battery goes dead, you will need to have the key reprogrammed into the computer, but first the battery has to be replaced, have you put a good battery in this yet?

Expert:  Tim Mohr replied 3 months ago.

do you still need help with this?