Odd /no cam sensor. Please help!

[Dirtman]

Im not good with obd1 systems. So I have no further value but Ill do you a favor and send up the bat signal for the wiring guru around here.

Calling @RonD

 

[RonD]

If you are running a 1990-1994 4.0l 60-wire computer, then the spark system is separate from computer

It has these 3 parts: https://forums.hybridz.org/applications/core/interface/imageproxy/imageproxy.php?img=http://i17.photobucket.com/albums/b81/BRAAPZ/EDIS/EDIS-6Large.jpg&key=ddfaa013169dd6c9cae2eb0a20b5937227598ea7d84cd3a108ff01cbf2fb1a84

The coil pack
The EDIS-6 spark controller
The Crank sensor and its tone wheel on the crank shaft pulley

Crank sensor is connected to EDIS-6
EDIS-6 is connected to coil pack

Crank sensor========EDIS-6==========coil pack

(people running there own fuel injection systems liked this EDIS system because it was also stand alone, doesn't "need" a computer)

The crank sensor starts the ball rolling, its a VR sensor so generates its OWN AC voltage, .5volt, so not much, but its the PULSE thats used not the voltage
This Pulsed AC is for timing, the tone wheel has a missing tooth(seen at bottom of pic) and that gap denotes #1 TDC
Each tooth is 10deg apart, so this is engine's timing
The EDIS-6 sends this timing Pulse to the computer, the computer doesn't even know you want to start the engine until it gets this crank sensor pulse from EDIS-6, computer then uses this Pulse to time the fuel injectors

The EDIS-6 then Grounds the Coils according to this Pulse to spark cylinders spark plugs in order

If you spray fuel into the intake, 50/50 test, and try to start it you can can either confirm there is spark(and at the right time) or confirm there is no spark
Quick and simple test

EDIS-6 modules rarely fail, never even read about one failing except in an accident, because they spark the coil pack they do run hot so are mounted to the rad support usually on the front side for better cooling, so they can be damaged in a front end collision


The Cam sensor was added to 4.0l OHV in Rangers in 1995 when Rangers also got the newer larger computer, 104-wire
These newer computer also had the EDIS-6 built-in so crank sensor and coil pack hooked to the computer
Crank sensor is still the main timing sensor, the only sensor that can cause a no start
Cam sensor has better "resolution", it spins at 1/2 the RPMs of the crank, so is better to time injectors for when intake valves are just opening so less wasted fuel coating the head ports
If the CEL(check engine light) goes off when cranking engine over that means computer is getting Crank sensor signal
If CEL stays on when cranking then its not

Calif sold vehicles required Cam sensors on earlier models of most engines, so like always there are exceptions to EVERYTHING, lol

 

[Rat Rod Bob]

Im not good with obd1 systems. So I have no further value but Ill do you a favor and send up the bat signal for the wiring guru around here.

Calling @RonD

Wonderful! Thanks again so much for you contribution to helping me keep some of my hair..

 

[Rat Rod Bob]

WOW Thank you SOOO Much RonD!
That is a lot of help! I really appreciate all the insight! I thought we were just loosing our minds! LOL
Still working on it but now with so much more understanding and direction to be able to diagnose. We thank you all again!