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Re: 5pin ecu to 4pin ecu Question
[Re: bigslant6fan]
#212262
02/02/09 09:13 PM
02/02/09 09:13 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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Do you have a 4 prong ballast or a 2 prong ballast? If you have a 2 pronger & the ballast has continuity then it's a seperate wiring issue from the # of pins on the harness as a 5 pin harness is OK for a 4 pin box if used with a 2 prong ballast. If the ballast is "open" grab a new one & several(2 prongers) are available(I think 1 for race & 1 for street) just get the right ohm one for your app. EDIT P5206436 street(1 ohm) & P2444641 race(1/4 ohm), both are 2 prongers.
Last edited by RapidRobert; 02/02/09 10:11 PM.
live every 24 hour block of time like it's your last day on earth
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Re: 5pin ecu to 4pin ecu Question
[Re: MoparTod]
#212264
02/02/09 11:23 PM
02/02/09 11:23 PM
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Joined: May 2008
Posts: 5,399 Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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Here is a photo of the circuit card from an orange box. The large black resistor at the top of the circuit card replaces the one side of the dual ballast resistor that goes to the 5-pin box. Bacause the 4-pin box contains this resistor, the box gets 12-volts directly from the ignition, and the single ballast resistor is only there to limit current to the ignition coil. There is one instance when the 4-pin box gets power through the ballast resistor, and this is when the key is in the start/cranking position on older cars. because the ballast resistor is very low resistance it should not be a problem, but if your worried about it you can put a diode accross the ballast resistor.
Last edited by 451Mopar; 02/02/09 11:25 PM.
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Re: 5pin ecu to 4pin ecu Question
[Re: MoparTod]
#212268
02/03/09 11:59 AM
02/03/09 11:59 AM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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On bypassing the ballast, our stock coils wont take 12V forever(what coil do you have) but the 4 pin ECU's take full 12V. the ballast does not care if it is being used or not. See if you have batt voltage at the upstream side of the ballast, the main feed wire at the ECU, which is the (pointed) terminal on the pentastar ECU connector & a certain amount(the ballast reduces it) of voltage at the coil positive terminal when the ign switch is in "run" position & this also feeds the blue alt field wire. In "crank" check if the coil positive terminal & the above mentioned ECU terminal are getting batt voltage. You can pull the NSS wire off of the starter relay during your checks to keep the starter out of it. EDIT the 'run" (& crank) battery voltage comes straight from the ign switch thru the bulkhead in 2 different wires
Last edited by RapidRobert; 02/03/09 12:41 PM.
live every 24 hour block of time like it's your last day on earth
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Re: 5pin ecu to 4pin ecu Question
[Re: RapidRobert]
#212269
02/04/09 02:51 AM
02/04/09 02:51 AM
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Joined: Jan 2003
Posts: 27,421 Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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The 5th pin on the 5 pin ECU is just an auxilary circuit to the ECU that goes thru the 5 ohm ballast. It only has power in the ign run position. It has nothing to do with the start circuit. Thats why when you go to a 4 pin ECU you can go to the 2 terminal ballast because the 5 ohm auxilary circuit to the ECU is not used on the 4 pin. The 4 pin ECU has 2 pins for the pick-up coil and one pin that comes from the coil and the last pin is 12 volts at key on. The coil gets fed thru the .75 ohm ballast with the 5 and 4 pin ECU. Ron
Last edited by 383man; 02/04/09 02:53 AM.
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