Question about 2004 Jeep Grand Cherokee
Could this be a security system problem
First check all fuses.
well if the security lamp is on, and the IMMobilizer light glows
it will never run. (by design) (2 seconds max)
so are the lights glowing?
no power going. (when,)
did you read the FSM on the staged events to get engine started.
my wild guess? (sad i have to ask) is it wont start?
1: IMMO not active
2: battery charged volts near 12.6vdc rested.
3: starter cranks fast. and ASD closes
4: ASD relay sees good spark and CKP, and CMP sensors.
5: engine starts, if #4 is good then it sustains running.
if not ASD drops out in 2 seconds. killing INJECTION.
it cuts the fuel pump too.
the PCM will throw a DTC error code (did you scan it cranking ??)
for if the ASD fails to OUTPUT 12v. at step 3.
the PCM closes it, then looks, and if output is bad, it ends this event and logs the failure..
to check the pump , it takes 2 people
one at the key, and one at the pump wires.
or you WILL miss the 2second event.
one way to avoid all that is to hold finger on the ASD relay
and keyon and see if it clicks closed.
if not ., no need to check pump ,its LAST in the chain,
if the ASD clicks and drops out, during that click the pump does run
for 2 seconds, min.,
if the ASD is dead, check the PCM control line to the ASD for
making coil energized in the ASD relay, (12vdc across it for 2seconds)
if the coil is energized, and the DTC throws, for bad ASD , it is.
if the ASD goes, hot only for 2 seconds, again use any $9
scan tool to see the error.
here is the scan too tests. most books forget.
1: scan tool connected.
2; Crank engine for 5 seconds, (min)
3: release key. BINGO, the ECU tells you why the ASD dropped out.
eg: ASD error, CMP error, CKP errors or others (spark?)
does RPM read near 250rpm cranking? on the scan tool?
Is TPS throttle angle near 100% (cutting fuel) ? bad tps. (cut wires)
fixing cars without a $9 scan tool , as sold on feabay is 100x harder.
get the tool and use it.
they rent them cheap or loan them for free.
not to be confused with a code reader, which are near useless.
Posted on Feb 12, 2014
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Posted on Jan 02, 2017
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