Need a complete wiring diagram '90 jeep laredo 4.0 of PCM,ignition,starting,ASD and other relay, also to see if there's any anti-theft for a crank no run problem. Fuel pressure good, injector pulse signal good, and unless there's a hiding fuse able link there all good

won't start means what,
will not crank./?if silent is the starter relay not clicking (now)
or cranks fast and will not start or does for 3 seconds and stalls?

in the fuse relay box , mostly in the engine bay
lost the operators guide? out of glove box.
will not crank at all (silent)
or cranks fast but will not start
or starts and stalls fast or slow. ????
will not run and stay running
yes engines can do that ,.

The ASD is the controlled by the PCM.
if the PCM sees danger it drops the relay
one danger is the PCM sees spark bad. and cuts fuel dead by dropping the ASD., dead on PURPOSE
for sure prevents FUEL fire, CRASH AND BURN as seen on TV
USA car, not told
USA A scan tool so it can tell you what is wrong in 1 minute flat.
buy one, rent or barrow one.?
step 1 is check all fuses. then scan it.
My first ASD was in my 88 jeep.
they could call it the ESD, emergency shut down relay or panic relay.
PCM logic controls it ONLY IT. !!!!!
NO anti-theft option on car or its LAMP angry.
right, ?
ASD causes of what?
11 pages on ASD
fuse 6 or 9 blown. bingo. ASD dead as a door nail. JB and Power center.
ASD dead injector power will be DEAD fully
ASD DEAD , ALL SPARK COILS HAVE NO POWER NOW



the asd coil pin low side is grounded (a transistor)
below see the PCM pin that does that.
and as I told you the PCM will kill the ASD on purpose for
at least 2 reasons (IMMO not happy) or senses spark dead
or he pre_cursors of spark dead, CMP or CKP (Or out of sync)
or the spark coil primaries dead.
but you failed to use a scan tool and work blind.



to use the scan tool do this

1. connect to OBD2 port 16pin at knees.
2. tool on.
3. key on, crank until it stalls. crank for 10 seconds.
4. release the key do not turn it off
5. let the scan too scan add see P03xx errors. DTC.
6. now key off. only NOW.

i got a 94 and mine did the same thing. turns out it had a bad fuel pump relay and a bad asd relay. i switched the horn and asd relays with them and it worked like a charm. give it a try, it cost nothing. all those relays are the same

The IMMO and PCM can not be willyynillyy swapped.
they are married by dealer programming
you did it all wrong.
what does changed PCM mean
a used one off ebay
rebuilt and the derp that sold it did not tell you it will fail not matched to IMMO
a new one from the dealer flat tells you as selected, it must be reprogrammed.

the PCM and IMMO are not PNP ,they are not plug and play ever.
and is why the car can not be stolen. (driven away with no good key)
by DESIGN and in many cases now, BY LAWS

some shops can also do this, with their JEEP license to do so, call em. ask.

You then have a ant-theft system problem an need to have the vehicle checked for DTC'S - diagnostic trouble codes . The ASD - relay supplies power to the ignition coils an too the fuel injectors .The ASD- auto shut down relay is energized by the engine computer - PCM . With the red anti-theft light on the PCM will not turn on the ASD relay cause a no start condition . You can check fuse an relays all you want ,not going to do any good . You need to see what the ant-theft systems problem is .

why not let the PCM tell you what sensor is bad.
and do the spark test, x 4 x 6? ???
if spark is all bad.
insert the diagnostic jumper wire.
then key on,
then crank for 5 seconds.
release key
flash code will tell you if any of 3 inputs are bad, 2 sensors or spark.
The ECU cuts all fuel if it even THINKS spark is bad.
fact.
why not test spark?/ like we do for 100 years now.
its no secret how.. like 125 million google hits. (what a million hits for every year./ LOL)

this trick works on all cars and jeeps from 1988 to now.
all. all with EFI and jeep used EFI in 1988, I had one,(renix sys)

your next learning path is the ASD relay,
its just a relay that kills injection, and friends.
it drops out of the ECU thinks there is no park for 2 seconds cranking.

Hi, pull out the ASD relay and use a 12 volt test light to interrogate the relay socket. Hook your test light clip to ground and probe the terminals of the relay socket. There should be one hot terminal when the key is off and 2 hot terminals when the key is on. One of these is the power from fuse 6 and the other is from the ignition switch. If these are good, suspect the PCM is not turning on the ASD relay or the relay is bad. You can check for the ground signal from the PCM by moving your test light clip to battery positive and probing the other terminals in the relay socket. Again, one terminal should light the light when the key is off and both should light the light with the key on. If not, the PCM is not turning on the relay, and you should suspect your anti-theft system. Please let me know if you have questions, and thanks for using FixYa.

Hi, the ASD relay powers the coil. It is turned on by the PCM. Reasons the PCM might turn it off are anti-theft system (when starting) or possibly low oil pressure/high temp (when running). Please let me know if you have questions and thanks for using FixYa.

Does the vehicle have spark ? If it does it is not the crank sensor . The ignition switch supplys power for the fuel pump relay directly ,ASD has nothing to do with it . The PCM - engine computer energizes the fuel pump relay by supplying a ground - if it see's a crankshaft postion sensor signal an if no anti-theft system problems . Do you know what a wiring diagram is ? Here free one's http://www.bbbind.com/free_tsb.html Enter vehicle info . year , make , model an engine size . Under system click on engine , then under subsystem click on fuel controls . Click the search button ,then the blue link. Third diagram down.

sounds alot the the pcm it controls the fuel pump and ign system but the anti theft would keep it from starting because the key has a transponder in it programmed for that vehicle and that would kill all ign if triggered

USA car
what engine???????????
wiki
2.8L VM Motori RA 428 Diesel I4
Complete engine specs[show] 3.6L Pentastar V6
Complete engine specs[24][show] 3.8 L EGH V6
times the starter will continue to run until key is turned off.
that is starter relay bad or the puter running it gone nuts.
or bad starter
next time when starter latches up, pull the relay
if it kills the cranking its bad relay or puter
if not, bad starter. all in 1min work..
and a very very serious first ORDER fix first problem
runs on test fuel. but you failed to keep it running for the 2 -3 second JEEP RULE.
if you had here is the results. (logic) hard.
1: i can keep it running with spray need a video?
yes, means ASD is not dropping out
2: no? ASD is killing the engine on purpose. and scan tool told you.

cranks no start
you said,
"No codes." if really true , there is no fuel pressure.!
if not true, its done wrong. so scan correctly THIS time.
is the skim light glowing in the dash cluster, if yes, it will not start
by DESIGN. SKIM is the immobilizer and DOES!

you must scan WHILE l its failing, not after, WHILE.
HOW TO SCAN correctly on JEEPS, (no starts)
key on, see scanner working? now, it must, if not ask.
crank or 5 seconds, (1 potato , 2 potata, 3,4,5.
release key, ( 4 and 5 are overkill but why not?)
do not turn key off or say 2 minutes, get PCM time to REPORT.

scan (2008 or newer scan tools work, CAN-BUS certified)
the tool then tells you why the ASD RELAY dropped killing starting (by DESIGN)
try to know SKIM is and option, so.... me blind can see car
http://jeepdied.com/ASD.html

runs on test fuel longer that 3 seconds, by hand, means.
all is working mostly, the fuel pressure gauge needs a jeep hose kit to work so/....... the pump needs power to work,



now the acid tests
i have 2. acid tests lacking a real scan too;..
spark timing light connected up.
you crank and spark dies, AFTER 2-3 seconds into crank/start
cycle means ASD dropped.
connect meter to injector 12vdc power feed its a daisy chain
12vdc dies, at 3seconds of crank, or dies
at 3 seconds of running,
if true PCM did that , and is ASD drop doing that
running any jeep for 1 second on test fuel is a waste of time
it tells too little
learn that jeeps can drop a ASD at 100mph
any time it wants. and only scanning while it drops
tells you why, unless the SKIM lamp glows,