In this video, I want to talk to you about the common trouble codes that I found on the
4.0-liter Jeep Cherokee.
First code I want to talk about is P0300, and then it will dance around to P0303, 304,
305, coil pack.
Pretty common problem, nice, easy repair.
There's four mounting bolts, pull it out.
I suggest doing the spark plugs at the same time if you haven't done them.
Maybe you did the plugs, and then that code came back, so you're doing the coil pack.
There's a little slight back door to this, though.
This also has a very common problem with the exhaust valve, carbon build up.
So if you do the coil pack, you clear your code, and you drive it, and it still has that
misfire, it's going to be...
If there's a TSB on it, Technical Service Bulletin, they do things like take the valve
cover off, decompress the exhaust valve, spin it.
If you want to get away from that and try something, do what they call a fuel injection
cleaning, and it will get on that exhaust valve.
And it's a pressure system that you put through as a cleaning.
It cleans the injector system and it gets into the intake.
If you can't have capability of buying it after market, you can go to a place that actually
has a machine that hooks up.
I would go that route, try that.
It's fast, it's cheap, and it will probably solve the problem.
Okay, so let's talk about code P320.
That's 320.
And it is a no-start condition.
We have engine light comes on, vehicle driving along, it might even die, dead, or crank excessive,
"Crank, crank, crank, crank, crank, crank."
Tank is full, you know you got gas, you'll end up with no spark.
And what that ends up being, 90% of the time, is the crank sensor, which is located straight
down here in between the valves and in the engine block.
It's mounted actually on the back side.
There's connectors down there also.
Just make sure you get a quality crank sensor and you should be all set to go.
So the last code I want to talk to you about is P1494, so 1494.
And it is about the leak detection pump in the EVAP system.
I want to a quick diagnostic with you.
So the leak detection pump location is right here, passenger fender well.
We have this little canister right here, and you've got that big hose, is the fuse box.
This is it.
That's your connector you're looking for.
And then on the back here, there's a vacuum line that goes in the back.
And that's coming from the engine compartment.
That's the vacuum hose that we're going to be talking about.
So you've got code 1494, leak detection pump problem.
What I want you to do is start the vehicle up first.
With it running, disconnect this vacuum hose, and check for vacuum.
You can just use your thumb, put a finger over it.
If it feels like it's suction like your house vacuum, and it's holding your thumb in there,
and you release it, "Shh, shh," that means it has good vacuum.
So you can reconnect that.
Let me shut the vehicle off.
I want you to get a test light and hook it up to the negative part here, and then the
pointy side.
Let me get you one.
So we'll do a quick diagnostic here so you can see if your leak detection pump is any
good.
So we have a test light.
We're gonna hook it up to the negative, and make sure it's working.
It is.
Now, I'm not gonna do the whole test.
I'm just gonna show you how to do it.
So the connector is right here.
I already took the liberty of disconnecting it.
It's got that little lock, that red tab, which is pushed down.
You're going to pull that up.
And then you're just gonna to pull this out.
I just want to show you the colored wires.
So if you look real close here, the first one on top is white with an orange tracer,
the middle one is white with a green tracer, and the bottom is a dark green with an orange
tracer.
That bottom one is our battery voltage with it running.
And this top wire is what we're going to use for a tester once it's running to see if the
pump is any good.
So we're gonna to reconnect it.
This is how you test it.
Once you know your vacuum is good, connect it.
Put the lock on just to make sure you get a good connection.
There you go.
And now, you're going to start it up with it running.
Test light is connected to negative, and you're gonna go down to there, and you're gonna to
check for battery voltage.
And it's running.
Oh, I got good battery voltage.
If you don't, then you have a circuit problem.
If you have battery voltage, then they want you to go to the top wire, which is the white
with the orange tracer.
Back probe it, and you're going to take your other end, and you're gonna to ground it out.
So you just gonna tap it on the ground like this.
And the whole time you're gonna to watch your light.
And if the light lights up and then doesn't, lights up and then doesn't, then you have
a bad leak detection.
So basically they're making sure that the ground is pulsating out of the leak detection
pump.
And if it doesn't, then the pump is no good internally.
So I hope you enjoyed watching this video.
I sure enjoyed creating it for you.
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