2.4L so did you first idle it to get over heat,220f so it can kickon,
scanning the ECT s,proving it hit too hot,, per SM>??
the key here is what, a real schematic,
and a simple voltmeter
some jeeps also have a modulated fan.(and driver for it)
fuse 4, PDC good. tested?
it goes to fan relay , contacts and then to fan motor circuit breaker
no air pocket on top of engine,making, ECT lie?
i the pcm sees ECT overheat
it puts 12vdc across the fan relay coils
if not the wire there bad,cut or pcm bad.
the PCM pin C2-p17 LG wire goes to relay pin 4
he PCM grounds this pin (using a transistor)
the relay closes, fan turns on.
Testimonial: "yes i ran the jeep until the temp got above 215 i jump with a hot wire to the fan and it comes on i also hooked a test light to the neg side of the battery and touched the green wire on the relay and it comes on"
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ok fan and relay good.
so why test at 215F? (it's too low)
is A/C working?
what other symptoms of overheat?
the upper limit on AF IS 259f. (50%AF)
So all fan software trips somewhere
between 200 and 259f. stat max to aF max.
the lowest hot spec. is 180f, or fails DTCs
see? many come with a 195F thermostat.
Chapter 7 lists a huge number or symptoms
did you review those?
the book says there is a DTC errors for overheat. P0217? p1489 to 1491???????
im reading the whole, Drivability book on car
it uses DRB-III to test PCM and relay and fan
so as not to overheat the engine,testing... this.
(the parked idle too long tests) is DIY methods.(it's ok but 215f is not it)
the fact of when the PCM grounds p17 LG wire
is key here,
The engine must really overheat,
The ECT must show that !
the engine ECT must read correctly for the PCM to turn on the fan.
some PCM have 2 trip points.
like
A/c on 220f
a/c off 240f.
jeeps with 2 speed fan, even more complex. (rules)
see? and is PURE SOFTWARE, you know that right? and can very by year,engine and country. USA version or export.
even calif cars are different, (smog laws)'
some turn the fan on ,the instant A/C is on.
other fans use a PWM pulse modulator module.
not yours it seems.
the cooling pages says
DTC set if fan relay fails (open or shorted)
and for over heat and under heat. both
I use an IR thermal gun , here,
at stat housing, to see true temps
if the ECT reads way low , then it's bad
or block is full of air.
i never trust dash gauges, ever, i use shop gauges, that show truth.
and then scan the ECU to see if it matches
my IR gun? (infra-red )thermal gun $15 cost.
I read all of chapter 7 (silly thing mixes 2.5L and 2.4L engines. (badly)
the secret is not there.
This secret seems deep,
GOT A/C (works?) can you turn it on?>
The PCM turns on the fan, 2 ways
AC on
and OVERHEAT and 215f is not hot.
if i disconect the plug from the coolant senser the fan comes on but the gauge stops working and enginge light stays on
the jeep does not have a/c
the new code coming up now is 1491
ok, no a/c
sure unplugging the ect will cause the PCM to go nuts
it will go to limphome mode, and run rich.
best to not unplug sensors or risk burning the CAT up.
if the sensor ECT scans and reads same as reality, real water temp there is need to suspect any ECt. ever,unless aIR pocket there.
what temp? thermostat in car? that is first
and forgot to ask. 180 ,192,195,200f?
"P1491"quote:
Radiator Fan Control Relay Circuit
An open or shorted condition detected in the radiator fan control relay control circuit. This includes PWM solid state relays."
unquote.
if the PCM sends the fan on command
and the fan or relay is unplugged
this is normal.(for self caused errors)
what makes you think car overheats???
there are like 20 symptoms !
steam.?
dash gauge only told me this.?
leaks from odd places.?
pinging?
DTC error, overheated, is big time clue.
lost engine power?
the fan only turns on or TRUE overheat.
ONLY (lacking A/C)
215 is not overheated.most cars are 220f
the fan test to prove the fan works
we overheat it on purpose
all cars overheat, parked, all do
with zero air flow ,parked, passing through the radiator.
so it idles and idles, and finally the first rule is hit, in pcm, like 220F ,
and the pcm turns on the relay.
its that simple.
i make sure my thermostat is ok first
and read the stamp on it, 180f or 195f and
then see that the ECT matches that as engine warms,up, the scan tool shows ALL that.
live data.
you have real scan too there,not just a code reader?
S
if its real cold outside, like in alaska
the fan may never come on parked.
outdoor temps matter, .
when parked and idling in moderate weather.
the engine will overheat. and the
thermostat opens fully, and the fan
takes over... at 220f so.
sadly the SM does not show this secret number.
they have what is called.
Hysteresis
comes on at 220F (typ. example xj)
then off at 200f, this PCM programming
hard coded, rules. "unchangable"
let me teach you about EPA smog BS.
the EPA dictates changes HERE,
many cars now,180f is *******. by EPA
and is now near 200f,
the FSM for your jeep repeats the 180f mantra
over and over, for vast numbers of other non related DTCs,this tells me that its NOT 180f
see my logic?
it says, pxxxx dtc is not checked below 180f.
so its near 200f
see my drift?
that means the FAN on temp on all cars with 200f tamps will NEVER be near 200f or below.
above, 220f is common on vast newer EPA CARS
THE JEEP.COM
SHOWS STAT. p/n as.
53010552AC
BUT FAILS TO SHOW ITS TEMPERATURE
MORE PAIN.
if 1491 trips all things connected,its real
take that the bank.
(after reseting it of course)
if car only overheats (real) at stop signs
and fan is DEAD THEN
ect bad. or
air pocket on top of water jackets and ect.
or running pure water for coolent. omg.
or fan wire broken from pcm to relay
for sure 1491. that wire.
after all the relay and fan work hotwired.
dead last PCM bad. $$$$$$$$$$$$$$
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