4 Pin and 5 Pin ECU Question

[74desertduster]

My 74 Dart currently has a 5 Pin ECU and I think I read some place that you can use a 4 Pin ECU in it's place. They are cheaper here and money talks right now.

Anybody know?

Thanks!

Brian

 

[yellowdartdave]

Yes, you can use the 4 pin unit on a 5 pin car and you don't have to change a thing!

 

[64_Barracuda]

Hmmm the way my 77 truck manual readout is if you have a dual ballast you have to use a 5 pin. How else would the secondary .5 ohms kick in then?

Not second guessing anyone but now I am confused!!!!

 

[74desertduster]

OK...turns out my connector and wiring is 5 Pin with dual ballast resistor....took off the old ECU and it's 4 Pin...been running fine for a while like this.

And the new ECU is 4 Pin and it runs fine.

Thanks

Brian

 

[dgc333]

Hmmm the way my 77 truck manual readout is if you have a dual ballast you have to use a 5 pin. How else would the secondary .5 ohms kick in then?

Not second guessing anyone but now I am confused!!!!

The 4-pin ecu elminated the need for the secondary .5 ohm input. If you use a 4-pin ecu that wiring and the second resistor in the ballast just sits there and does nothing.

Most of the aftermarket ecu's available today even if they have 5 pins in the connector are of the 4-pin design internally.

 

[64_Barracuda]

Makes sense Dave thanks!!! I lost the primary side on the ballast once and the truck would start but it took for ever. I later found out that the primary side puts out 12vdc to the coil where the secondary side is 8.6 VDC.