Check this - http://fordfuelinjection.com/index.php?p=25
I would replace both.
Continuous memory codes are intermittant failures that have happened multiple times so the computer stores them - so your TFI might test good (when the truck is running) and then crap out later.

 

i had the TFI module checked out at the auto parts store and they said it's fine. i also checked the OHMage of the TFI module at home and it also shows fine. i have allready replaced the HEP/PIP/insert your own name here inside the distributor.

i checked the voltage at the harness going into the TFI module at all 6 pins. i am not able to determine which pin coinsides with pin #1 through pin 6. this probably doesn't matter since i am NOT getting near 12 volts at either pins 1 and 6. i'm only getting 3.9 and 4.5 volts. all the other pins i'm getting the full 12 volts, except for pins 3 or 4 since i don't have anyone to help me roll the ignition to START to check that voltage.

my repair manual says that all 6 pins need to be within 90% of total battery output (12.5 volts).

i am now seeing that the ignition switch itself may be bad since the repair manual says to check it out on this test and from another seperate test which did not pass.

opinions?

 

ok. problem fixed. i finally got time to replace the plugs and wires, i also replaced the dist. cap.

the truck started right up. i went to hook up the scanner to the plug under the hood and then the truck cut out.

turns out one of the fuel pump relay wires was extremely corroded that the terminal end broke off, hence cutting off fuel to the motor when i was handling the wires in that area for the scanner.

whether this was the original problem in the begining, i wouldn't know. but now i gotta run to the store and grab a terminal so i can hook up the fuel relay back on.

and here i was blowing my nonstart problem out of proportion with the TFI harness and module and the distributor...

thanks, guys.

 

Sorry I didn't get back with you. The 40 minute drive (one way) to work sucks up my time.

Oh yeah, check Murrary's for tools that they rent. They may rent out tachometers.

 

it's cool. during all of the confusion i think i've found my vacuum leak source while wiggling random vacuum lines. one of the lines going to the vacuum actuator to control the trap door to the HVAC broke off. i pulled off the connection at the manifold and plugged that hole. when i started the truck earlier today the idle didn't sound so high anymore. plus whenever i through it in drive or reverse the idle did not drop as much as it used to.

plus the thing kept running without dying at random like it did when i searched for that vacuum leak previously, except when one of the wires to the fuel pump broke off.

thanks anyway.