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Need Help- '94 XJ 4.0L died, won't start. few codes.

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Old Nov 15, 2016 | 02:56 PM
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Year: 1994
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Default Need Help- '94 XJ 4.0L died, won't start. few codes.

1994, 2wd 4.0L auto trans.

Ran fine, was going down the road and hit a large bump, it died and will not start again.
May just be coincidental.

Codes I am getting,
1)Throttle position above maximum allowable voltage.
2)Charge temp sensor above maximum allowable.
3)Can't rember the wording of the last code but it was about the coolant sensor and I found the one near the firewall nearly split in half.
Does anyone know the correct part# for a BWD sensor?

Fuel pump is not coming on that I can tell.

What/where is the charge temp sensor?

Wtf has happened here?
I had to leave it where it broke down so I would like to get as much knowledge as possible before I return to it.
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Old Nov 18, 2016 | 07:16 AM
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I've been searching and reading about common issues,
I've found where one person claims the bad tps caused the computer to think that the engine was flooded and wouldn't allow the fuel pump to come on.
I have only found this once in all the searching I've done so far, just wondering if anyone else lows whether or not this can happen.
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Old Nov 18, 2016 | 08:18 AM
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Year: 1994
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#1 Could be throttle position sensor #2 Sounds like ambient air temp sensor. It plugs into the header near the throttle body. #3 is the temperature sender. Make sure to differentiate whether it goes to dummy light (my 94 does) or a gauge.

BWD part #'s:
1) EC3313
2) WT3023
3) WT903 - But be sure to check it goes with light or gauge (whichever you have)

Good luck.
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Old Nov 18, 2016 | 09:05 AM
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Thank you for the help bigVOLharp98.

I know it needs the coolant temp sensor and the tps, being that it's so common to fail, but I am stumped as to why I lost fuel pump function at the same time.
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Old Nov 21, 2016 | 04:03 PM
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Ok so I didn't make any progress but have some updated information.
Still seeking help & opinions.

20 amp fuse under hood for engine control was blown.
Replaced it and I have 2 codes added to the list.
New codes are:
Short in radiator relay
And
Short in A/C compressor clutch circut.

Idk if I have a short in the wiring or what's going on here.
I now have fuel pump function but no fire.

The crank position sensor has about 10k miles on it as well as the ign coil.

It has 157,xxx miles on it.
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Old Nov 22, 2016 | 07:22 AM
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Sounds like electrical wiring has a short. Break a wire or short one out when hit that bump? You will need to be handy with a voltmeter and check around for +5vdc on sensors like tps, cts, iat, ckps, cps,.. as I think they share the same feed. If that feed is dead they will code and you wont run.
I saw a great utube video of a shop instructor tracing down a similar problem with a scope f or his class, turned out to be a short in the wire close to the cts, if memory serves.
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Old Nov 22, 2016 | 02:46 PM
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Which one is the cts?
I know the abbreviations on the rest.

Should they have +4.9 volts on every pin for every sensor? Because mine seems to.

The ckps doesn't have voltage at the plug....
It ohms out at 2.9 ohms as well.
No extra code with it unplugged.

Cleaned grounds on engine block, near manifold and near pcm.
Both ends of each and left the body sheet metal with bare metal showing.
Replaced battery to engine wire with new one.

Lost a/c clutch code and radiator fan realy code.
The coolant temp, charge temp and tps have codes for above maximum allowable input voltage....
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Old Nov 22, 2016 | 04:50 PM
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Coolant Temperature Sensor- right at the upper hose to block top front engine
No, at least the tps should have a +5 and a ground. MAP also. The other is the signal from the tps depending where the wiper is on the resistor. You need to unplug it to check for sure but sounds like lost ground from the pcm.
You need to get this to a shop off the side of a road.

Last edited by 97grand4.0; Nov 22, 2016 at 04:55 PM.
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Old Nov 22, 2016 | 06:08 PM
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Originally Posted by 97grand4.0
Coolant Temperature Sensor- right at the upper hose to block top front engine
No, at least the tps should have a +5 and a ground. MAP also. The other is the signal from the tps depending where the wiper is on the resistor. You need to unplug it to check for sure but sounds like lost ground from the pcm.
You need to get this to a shop off the side of a road.
Will be at my shop soon.
Is that an issue inside of the pcm?
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Old Nov 23, 2016 | 02:22 PM
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Waiting on a tow truck to cone get it now.
Took the advice of another and spliced a ground wire into the black/ light blue wire, did it at the intake air sensor.

All my trouble codes went away when I did this.
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Old Nov 23, 2016 | 03:34 PM
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Originally Posted by Constantine
Waiting on a tow truck to cone get it now.
Took the advice of another and spliced a ground wire into the black/ light blue wire, did it at the intake air sensor.

All my trouble codes went away when I did this.
So I'm taking it since u waiting on the tow truck that didn't make it run.
Kind of supports the idea that the ground got broken but be advised I don't think the pcm ground that it should have is the same as the chassis ground.
So at best you may be on to something.
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Old Nov 23, 2016 | 06:07 PM
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That wasn't actually a fix, it was more of a test to insure that lack of pcm ground was the issue.
I had some time on my hands waiting on the driver to arrive.
I'm thinking somewhere between the pcm output and sensors the ground has been interrupted.
I'm going to look at the part where the seperate wires come together to make one near the master cylinder to see if something has come loose inside there.
As well as a thorough inspection of the wire.

Just consulting here to see if this may be a step towards fixing the issue.
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Old Nov 23, 2016 | 06:14 PM
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Sounds like you're barking up the right tree. As I mentioned, the guy in the video found a break in the harness along the fuel rail by the coolant temp sensor. This is where the field service manual comes in real handy, you can download one for $7 at Pacific Coast Manuals
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Old Nov 23, 2016 | 06:31 PM
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Alright, I will look into that download.
A more in depth wiring schematic would help me alot.
This is the best I've found


Thank you for your input.
Electrical is my one weakness.
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Old Nov 23, 2016 | 06:35 PM
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The one in the fsm is the best, all wires are in color, and of course it is above all deadly accurate. I did find this one but would not swear to the accuracy Looks like half a dozen sensors all share that Black/Light Blue ground.
http://repairguide.autozone.com/znet...52800a9e06.gif

Last edited by 97grand4.0; Nov 23, 2016 at 06:43 PM.
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