What is this??

[loborojo338]

I have an 87 YJ with the 258 and I am going to do the TFI upgrade and was looking under the hood and noticed that the yellow wire from my coil goes to a ballast resistor on the firewall:? and then comes out of the resistor an goes to the diagnosis plug mounted by the battery.Now the previous owner said the computer was bypassed but I have not verified that yet. The Jeep will not idle but runs fine once the RPM's are up. I also plan on doing the Motorcraft upgrade.My question is can I bypass this ballast resistor and go on with the TFI as described in the forum? Thanks in advance for any help.

 

[jay79cj7]

If you have a full 12V in your ignition circuit, which you probably would if you remove the ballast resistor, you risk burning out your ignition module, leaving you stranded somewhere. It happened to me twice before I fixed it. You can do the HEI/TFI hybrid mod (TFI with HEI module) and not worry about that.

 

[loborojo338]

So should I leave the ballast resistor in when I install the Ford ignition system (i.e.,cap ,rotor,new TFI coil and cap adapter)?

 

[lah2420]

My 87 didn't have a ballast resistor anywhere off of the coil. It had a full 12 volts. Mine is also an early 87, so maybe that is the difference.

 

[SenorCole86]

Leave the ballast resistor in there until you do the HEI upgrade. It's there for a reason and should not be bypassed.

 

[jay79cj7]

Normally they don't have ballast resistors, they have ballast wires. As are many parts of the Jeep, things get changed and rigged to work over time. If you are going to use the stock module, do not use 12v. It should be around 9v I think. If you spend an extra $20 on the HEI module as you do that conversion, them yes, you can scrap the ballast.

 

[loborojo338]

Thanks for the info. I got it converted today. It works Great