Question about 1990 Ford F150

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All new ign parts no spark need to replace pcm ? where is pcm?

Cant get truck runnin no ign . plugs, wires, coil, starter, relay, what else? i want to change pcm but cant find it can you help?

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Have you replaced or checked the crank position sensor? I think your truck has one. You didn't include the engine type your truck has so this is the closest I can give you:
F150 CPS

Posted on May 13, 2010


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1 Answer

Ignition coil problematic primary feed

older post.
how many miles, how many miles for the last tuneup.????

The PCM CREATES spark. on all cars since about 1991.
the only changes are where they hid the IGNITOR.
or how may spark coils you have.
my guess, is your enigne is 3.8L just like my 08
where is the coil pack, well see those spark plug wires.
the go directly to the top mounted coil pack. see that?

the PCM monitors the rail coil , the 3.8 has a 3 COIL pack.
and each coil runs 2 cylinders. like this.
so what is the first thing to do here.
easy , put in new spark plugs.
try doing the tuneups. in the glove box guide.
page 433 , at 102,000 miles. spark plugs and cables.
mine has only 60,000 miles, and they both were bad.
spark plugs and HV, wires so I upgraded to NGK mag wires.
and new NGK plugs.
if it still fails, then try a new coil pack.

HV= high voltage wire sets.

Mar 07, 2014 | 2008 Jeep Wrangler

1 Answer

No Spark

Is the PCM controlling the coil's ? You have B+ voltage at the dark green with orange trace wire at the coil pack ? The other two wire's go to the PCM - the PCM has transistor's that supply a ground to those two wire's when signal from crank sensor is seen . Opens an closes to build up voltage an to release a spark . You can test this control with a test light . Video's on youtube.

Nov 25, 2017 | 2003 Chrysler PT Cruiser

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Check that the wiring harness to the coils is getting 12v, this will confirm if the pcm is sending a signal for the sparks to fire. Check the ignition coil is sending spark to the plugs with a spark plug tester.

Oct 14, 2013 | 2002 Chrysler Concorde

1 Answer

Why will it not start

does it backfire ? if so try resetting distributor , check timing , also check compression .

Mar 13, 2012 | Cars & Trucks

1 Answer

I have replaced the spark plugs, wires, coil, distributor cap & rotor, coil wire and my 92 wrangler, 4.0 L HO will crank but not start. I pulled a plug and grounded the casing, cranked the engine and...

a good start, (no pun) spark renewed parts
good. always good. a full tune up.. for real. (spark)

that distrib device is called a CMP, cam sensor!
the flywheel has CKP sensors. to...

but the reason you cant find this is you lacking a scan tool.
the PCM can cuts spark for many reasons.
the ASD relays does that. by command of the PCM

The PCM drops the relay for 1 to 8 reasons.
minus 1 , your car has no IMMO SKIM key.
but here is how to diagnose all JEEPS, (not fake MK jeeps)
first is to understand the ASD relay.

to do the tests takes 2 persons, unless you are a Xmen. guy.
the JEEP LAW OF 2 SECONDS must not be ignored,
2 full seconds. rule.
this rule applies to spark and fuel,

1:fuses good. test them.
(key on CEL glows, check engine lamp must glow or PCM has no power) does yours?
2: man 1, cranks. (car can crank with DEAD PCM) yup.
3: man 2 , (or WOman) tests spark using a test spark plug
at say #1 front, (easy bend over) lazy we are.
use a real spark plug. ok>? new. or not shorted.,
you ground the shell (this is a 100 year old test, not magic and is done by every mech, alive.) google how to test spark
and not get electrocuted, (got a pace maker?, keep hands in pockets)
4: the key on ASD closes and engine cranks and spark happens for 2 seconds, or not, if the spark ends just as the ASD drops
a hard cold fact.
if there was not spark for 2 full seconds, then sparks dead.
the PCM must be scanned.,
if you cant scan you get to shot gun all day.
i have a scope , you dont but i can see if the pcm is pulsing the COIL.
you cant. so get to guess that too.
if the PCM is not pulsing said coil (lets pretend coil is good, i can bench test them, easy)
then the PCM has BAD INPUTS>
or CKP
tops the list. of shot guns, seems like 1000s replaced here
and not one fixes it.... but goes on.. .. and on because....

best is to own a scan tool to fix any jeep 1991 to now.
or go broke every time a part gives up the ghosts.

the keyon 3 times tests.
can find problems , but NEVER ALL problems, its blind to many.
its just toy really, but has value, if if works.

Mar 26, 2017 | 1992 Jeep Wrangler

3 Answers


Ground wire to radator support on top left right next to hold down bracket. Or possibly crank sensor.

Jan 18, 2010 | 1992 Jeep Cherokee Briarwood

2 Answers

Replaced..starter..ign switch..relay

check the compression change spark plugs and wires and check distributor and cap

Nov 03, 2009 | 1994 Nissan Pathfinder

1 Answer

Engine cranks wont start

i do believe that's what it is if it will not let get a diagnostic or if it will not let you access the computer the computer is bad.

Aug 26, 2009 | 1997 Dodge Ram 1500 Club Cab

2 Answers

1985 gran fury. i've changed the distributor,the brain, the coil, the ign. relay, and the rotor and cap. the car fires when it wants to . more like it starts every other day i have no clue what to do

I'm going to assume you have a 318? Also going to assume that the wires and plugs are in good shape? When it's not starting, do you have spark? If not, do you see spark for any part of the time when you crank it? Have you made sure that the carb is OK and not flooding the engine?
What I just said is'nt a "fix...yet...I need to know this stuff first.

Jun 14, 2009 | 1985 Plymouth Gran Fury

1 Answer

1996 S-10 cranks but no fire

did you check to see if fuel pump is pumping. fuel filter isnt clogged is it? but you're sure there is no spark. because if there is spark it could be air flow problems.
and you changed the ignition switch so that's not it, how about the starter. is there any noise coming from the starter when you turn key? if it isn't lined up right.
there has to be spark if you did what you said take off a wire at night and try it . electricity to start goes, ign switch battery starter(is there a relay on s10s cant remember), the alternator is here coil/distributor to wires to plugs to gasoline

also it could be the wires coming from the battery , check them for corrosion. if they are really corroded could be problem. and make sure your ground is good contact. ive seen corrosion inside wires causing no spark.
just a few ideas to check.

Feb 25, 2009 | 1996 Chevrolet S-10 Pickup

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