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John Mc
John Mc, Ford Technician
Category: Ford
Satisfied Customers: 6240
Experience:  19 years Ford Lincoln Mercury experience
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1989 Ford f350; 5.8 no start;no spark at coil; new TFI; new

Customer Question

1989 Ford f350; 5.8 no start;no spark at coil; new TFI; new PIP; new coil; new ecm; resistance test on tfi test good; ign. side of coil is hot with ign. on; however tach side is also hot with ign. does not blink test light in crank position with spout connector in or out. resistance on coil test good. opened harness from ecm to engine found no pinch's, cuts or melted spots; disconnected four L.H. fenderwell connectors checked connections and pins all good. whats next
Submitted: 8 years ago.
Category: Ford
Expert:  John Mc replied 8 years ago.

Hello, I am John, a Ford dealer technician.

I hope I can help solve your problem quickly and accruately.



First off a few questions. With the key on and engine off does the check engine light come on? If not check the pcm relay. This is the brown relay on the drivers fender. If the light comes on does it turn off when the engine spins over? If not let me know and we'll go from here.


I hope this answer has been helpful to you! If you have any further questions please feel free to ask.

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John Mc and 3 other Ford Specialists are ready to help you
Customer: replied 8 years ago.

mil does come on; forgot to let you know that; dtc's are 21 and 85 ; etc and canisiter purge

Expert:  John Mc replied 8 years ago.
Does it turn off once you crank the engine?
Customer: replied 8 years ago.
sorry for the slow response ; yes engine cranking will cut off with key; eec and fuel pump relays new; circuits are good. koeo pass 11; continious is 21 amd 85
Expert:  John Mc replied 8 years ago.
sorry just trying to make sure I have this right. When you crank the engine the light turns off correct?
Customer: replied 8 years ago.

correct; sorry on in key on ; off in crank

Expert:  John Mc replied 8 years ago.
Ok, this means that the computer is getting a rpm signal from the distributor and module. So this is working. Now I want you to disconnect the 2 wire plug on the coil. Test for power on one side, the red/green wire should have power with the key on and engine off. Now take your test light and connect the clip to the + post of the battery. Now while an assistant cranks see if you have a pulse. Let me know what you find.
Customer: replied 8 years ago.
not so sure on the colors; however i believe that white w/ blue tracer is positive side of coil; it does have 12v. w/key on. green on neg. side. hooking test light to test positive; clip to neg. battery both side of coil are hot w/key on. sorry no longer at vehicle to test for negitive clipping to pos on battery ; can retry in the a.m. and advise
Expert:  John Mc replied 8 years ago.
Make sure to test with the coil disconnected from the wire harness.
Customer: replied 8 years ago.
from last conversation last night; this coil wiring is pos. side white/blue tracer is positive with ignition on. negitive side is greenwyellow tracer checking neg. with test light clipped on pos. side of battery ; will not light test light ; will not pulse test light; harness is disconnected ign. in on position or start position same result
Expert:  John Mc replied 8 years ago.
I think I found your problem on your truck. You have a ballast resistor and the book says it is inline with the green/yellow wire close to the steering column. I personally do not know where this is. From the info i have this is located between the coil and pcm close to the steering column somewhere in the harness. I hope this helps you out. If you need more help let me know!
Customer: replied 8 years ago.
have already found and tested resistors ; they are located in harness from eca feed from pin #4 on eca through 22k ohm resistor splits one to coil neg. the other to tfi. tested resistor ; ohm'ed out wir test good. just did this before last reply. seems as though pip signal into eca is not happening or spout out of eca is not happening; however wire's ohm out resistance test meets spec's ;new eca;new tfi; new pip; new coil. harness has been opened from eca to L.h. bank to breakout for coil ; no visable defects
Expert:  John Mc replied 8 years ago.

I'm going to post a wiring diagram for this system for you to reference. You need to test resistance, test resistance to ground and resistance to power. Make sure the battery neg is loose or you will fry your meter. You are going to need to check all the circuits between the pcm, coil and tfi module. Sorry I can't help more, hard to do from the other side of the computer ;)


Click here for diagram



John Mc