>>> WIRING DIAGRAM QUESTIONS <<<

[MIDNIGHT RIDER]

I have been perusing the wiring diagrams in a couple manuals that I have.

Of course, there are plenty of dead-ends leading to stuff that the truck never had or just does not apply anymore.


I keep seeing reference to an "Extended Useful Life Sensor" and also an indicator-bulb for same; what on earth is an "extended useful life sensor" and what useful purpose could it serve ?? (I am doubting there is one on my truck.)



Now, a bit more necessary information concerning the ignition-switch wiring.

START-position Pin I2 has a BRN/PNK wire that connects to the various circuits powered by RUN-position Pin I1 via a RED/LtGRN 1.1ft RESISTOR wire.

Please explain what function this RESISTOR wire connecting the START and RUN positions serves.

Thanks.

 

[alienturtle]

this may not answer your ? but im just posting this hoping it might help you with something you come across its from when i re wired my ignition with full relays. I think that br/pk is for gassers

Ignition switch wire colors-
32 start ckt - Red/Light Blue (R/LB)
16 ignition ckt - Red/Light Green (R/LG)
262 ignition bypass (jumps out the ballast resistor inline on the ignition coil) - Brown/Pink (BR/PK)
297 accessory 1 - Black/Light Green (BK/LG)
977 Proof 1 ckt - pink/white (P/W)
41 Proof 2 ckt - Black/Light Blue (BK/LB)
687 Accessory 2 - Grey/Yellow (GY/Y)
37 Battery. - Yellow (Y)

 

[SparkandFire]

Our '89 Bronco (351 fuel injected) had the "extended useful life module" and at aroun 60k miles on the odometer the check engine light came on.

My dad took it to his shop and hooked it up to the code reader, and couldn't find any codes... So he looked up the module, found it on the inside firewall, and stuck a paper clip in it, CEL went out and all was good...

So, apparently its a magic box that sends you scampering to your Local Ford Dealer at around 60k miles to "help extend the useful life of your vehicle" by getting a couple thousand dollars worth of "emissions related" repairs.

Also - the resistor wire bridges the switch point gap between the "start" and "run" switch positions. So your engine doesn't die when the key is in transition between start and run. Mostly important for EFI vehicles because a spilt second loss of "IGN" will shut the computer down for sure. I would imagine the inductance of the fuel solenoid in the IP on our trucks would allow the engine to "ride through" the switch transition.

 

[MIDNIGHT RIDER]

Thanks for clearing up those mysteries.

Seeing as how I have push-button START, then I can disregard that resister wire if it were to happen to be in there.

I am soon removing all functions away from the factory key-switch; there aren't many left on there anyway, due to my years of improving things electrical.

 

[alienturtle]

yeah when my mechanical switch that was hooked to the rod got a little toasty i decided to make everything with relays.

i now have push button start and everything is controlled by 4 relays under the dash. The rod and ign switch are in the track

 

[franklin2]

The extended useful life sensor is just a timer for emissions on gas engines with EGR valves. The EGR valve leads a hard life on any engine, and needs servicing on a regular basis to keep the engine running well. All engines with EGR valves have this problem of clogging with carbon, and the valve burning out. Ford's timer was there to make people take their vehicle in to repair/replace this before it gave trouble.

The resistor is also for gasoline engines with the duraspark II ignition system. The resistor has always been there for points systems also, it's not used on TFI ignition systems for EFI vehicles and some computer controlled carbed trucks with TFI systems.

The resistor controls the current delivered to the ignition system. It drops the voltage down to the coil +, which controls the current through the coil and the module(or points). There is usually a bypass to this resistor for starting only. This gives a hotter spark during starting so it fires quicker in very cold weather, and then reverts back to the resistor during normal running.