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  #1  
Old August 11th, 2003, 18:48
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Lucas Lucas is offline
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Trouble codes... mean anything?

Trying to stop the shotgun approach of fixing my starting problem (Already installed a new fuel pump, needed anyway though), I decided to check my codes as per the instructions on gojeep.rockrawler.com. I pulled a 12, 22, 55.
The 55 is the end sequence, the 22 is when I disconnected the battery, and the 12 is supposed to be a faulty coolant sensor, or short in the line.

I was expecting an 11, for a bad CPS. I ran to the engine bay, disconnected the CPS connection, the MAP connection, and dis/reconnected the coolant sensor on the thermostat housing. I ran for codes again and pulled another 12,22,55.
No codes pulled for the disconnected CPS or MAP sensor.
What gives? Am I just reading diagnostic problems from when before the jeep died, or is the check engine light diagnosis real time?

Just some backround:
Jeep died on interstate after 1/2 tank fresh gas
turns over fine
all relevant relays recently replaced
new optima
replaced suspect fuel pump
ALL electrical connections disconnected, inspected, greased w/dielectric

Was going to replce CPS , but codes check out ok. Any suggestions?
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Old August 12th, 2003, 08:56
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OK the "22" that your getting is NOT a battery disconnect (that's the 12)...

So aside from disconnecting and reconnecting the coolant sensor (your 22 code) what'd'ja do there .. ?

Seems to me that measuring the voltage available to that bad boy and verifying it's proper operation would be THE repair. If the PCM assumes that the engine is cold (or hot), the PCM will change timing and mixtures...

I'd work on resolving your code 22 (coolant sensor output out of range) - that probably won't fix a no start (if that's what your issue is - no too clear in your post) unless you find that the CTS's power wire is shorted to ground.

Next time you disconnect the battery - try disconnecting ALL of the PCM's connectors and inspect them for corrosion before reconnecting them - sometimes with that being outside under the hood, the "odd" problems can be fixed...
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Old August 12th, 2003, 10:23
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Already inspected, cleaned, and greased every connection in the engine bay. My main problem now is no spark. Swithch 12 and 22 in the above post.

Why did the Jeep not give me codes for the unplugged CPS and the unplugged MAP?

Ive started the Jeep before without having the coolant sensor hooked up (replaced a thermostat) and it started right up, just a little rough till I plugged it back in. I just need spark right now.
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Old August 12th, 2003, 12:44
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Spark is determined by the CPS and the Distributer's Sync output - you can inspect both easily - I'm not sure how fast the codes would store if the CPS just died on ya --

Do you have an OEM Tach? -- Does it register all the time while cranking (if it does, since it's driven as a function of the CPS data stream, your CPS would be good enough to drive the ignition primary...)

I've seen a running Jeep (xj 4.0 actually) die mid-traffic with a rotor that failed - just the bar dropping off of the rotor -- tach indicated cranking speed and there was good injection - owner didn't think to look at the rotor, instead changed the CPS...

Did you verify that you have no spark on the coil wire (timing light is handy for that)?

Do you have injection (verified fuel entering the cylinders with adequate pressure in the rail after your pump-job)? If not, do you have injection pulses (noid light, back probe, scope, or ??) the injection data is derrived from the same sensor sources... so you should NOT have pulses with no spark coming outta the PCM...

Any particular reason that you used a non-conductive grease in electrical connectors?
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Old August 12th, 2003, 13:28
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I checked the cap and the rotor. A bit dirty, but once cleaned out they both still looked really fresh.
I JUST replaced the CPS and got nothing. I was checking spark by using a wire from the cap on an old plug and laying the threads down on a valvecover bolt. I was at my parents house when this happened and I left my multimeter in a city three hours away.

Fuel pressure good, don't have tools to verify pulse.

I used dielectric because I thought that was what I was supposed to do. I thought it kept electical contacts clean by preventing exposure to air and maintained the cleanliness of existing contacts.
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Old August 12th, 2003, 14:27
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New CPS, NO register on the tach when cranking up. No new CPS code. Looked inside dist, very gunky, and shaft has about 1/2 mm radial play. How do I test the synch sensor?
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Old August 13th, 2003, 14:25
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I would also check you ignition coil. I have a 93 country also with the same problem and it turned out to be a bad coil. I replaced and checked all the same stuff you have, but in the in the coil fixed it.
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Old August 13th, 2003, 15:40
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If the ignition coil was bad, but everyting else is OK, wouldnt I get a reading on the tach?
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Old August 13th, 2003, 16:35
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WOW, thanks! New coil and im back on the road!
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