I have one code that I just can't seem to figure out. This is for the fuel temp sensor I believe, and from what little I was able to find while searching, it should be on the fuel filter head. Well, there's a problem, it appears as though the PO has done away with the original set up, changed out the filter head and installed an electric lift pump. Does anyone know how I'd go about defeated this P0180 code now? I've tried pulling the fuse, and checking the relay for functionality. No dice. Thanks for any bone someone could throw, I'm not sure I'll pass inspection with this CEL on.

If you can get someone to tell you what resistance is measured across the temp sensor terminals, the heating element, and the WIF sensor... under 'nominal' conditions, you can probably replace any one of them with a resistor of similar value (Radio Shack). In the case of the fuel heater, if it requires a load to be happy, don't forget to use one with an appropriately high wattage rating.

The values may be available in diagnostics form somewhere, otherwise, whip out the ohm-meter and see what a stock model gives you.

Mark

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

Ok, here is some additional information on the theory of operation. You care because the fuel rail pressure is adjusted in part based upon measured fuel temperature. If the sensor is detected as missing, the default appears to be to reduce rail pressure in order to protect the engine from hot-fuel (etc).

Check out the following: http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=22803&start=0

If you can't replace it with something that works approximately the same - actually changing resistance with fuel temp like the original - keep in mind that under temperature extremes an important 'safety factor' may be lost.

Putting a fixed value resistor will get you back to normal pressures and no CEL, but may leave you exposed in hot temps, and possibly leave you with starting or drivability issues at colder extremes.

Mark

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

I totally agree with Mark. If it was me I would replace the head with a new OEM.

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2005 CRD Limited

Totally disagree

What you have is a Racor fuel head - standard on the 02-04 2.5L and an upgrade to the 2.8's - if properly installed.
if is a big 2 letter word....
here are a couple of good installs
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=98&t=36977

http://liberty.eurekaboy.com/racor.htm

my concern is that the lift pump install isn't particularly clean - and I don't see connectors - so I'm concerned someone didn't clean up the details
and the details can give a lot of problems.

there are 3 electrical connectors to the fuel head - WIF, Heater, TC - it'll run fine without WIF or Heater (until it's cold)
however you do have to have a TC signal to the computer - I don't even see the TC wiring anywhere there
it may be tied to the side like this


even if you want to reinstall the original head - you need the 3 connectors - see if you can find them


and on troublehsooting the TC

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2005 CRD
stuff
Skeptic quod gratis asseritur, gratis negatur

Actually, Mark's point was only that an informed decision should be made with regard to the downside / potential consequences of running with the fuel temp sensor missing or disabled; that in certain circumstances it adds value in the form of a safety in certain high-temp situations, and possibly drivability and performance in certain low-temp situations.

Ideally, if a way could be figured out to make use of a similar fuel temp sensor in either the OEM or Racor unit you'd have the leak-free fuel filter head and retain the performance/safety functions of the fuel temp sensor.

Will a 2.2k ohm resistor be good enough - probably, in most cases. Attaching the original puck and having it secured in the engine compartment will probably be Ok - but could react to ambient temps in the engine compartment which are high enough to cause the ECM to reduce rail pressure in some cases where the fuel isn't actually hot enough to do so..

If you're informed, I'm happy, do whatever suits 'ya.

Mark

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

Thank you guys both for replying, at this point I just need to get the car inspected and legal to have on the road. I have a question, just to make sure I'm not miss understanding something...

"The thermocouple has 2200 ohms of resistance at 25C. You could disconnect the temp probe and put a 2200 ohm 1/2watt resistor across the leads to simulate the thermocouple. Verify that the CEL clears, If it does, then you have a problem either with your Thermocouple temp probe or the wiring.
Caution, There is 5 volts between the leads, don't short the leads together when the key is on, could damage the ECM.
2200 ohm 1/2 watt resistors are available at any radio shack, 5 for a buck."

Just to be painfully clear, the resister can in no way short the leads, he's merely cautioning against making a mistake and have the two leads somehow connect to one another without a resister between them? Like slipping with the screw driver or something?

5V / 2200 ohms = 2.273 milliamps or .002273 amps

5V / 0.001 ohms = 5,000 amps (theoretically)

So yes...should be fine as long as you do not create a direct short between the leads.

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2006 Liberty CRD Limited

Provent @ 43,000 km
SEGR in progress
SAMCO Sport hoses @ 48500 km
Goodyear Wrangler Duratrac LT225/75R16

Ahem... division by zero is undefined, current would be off the charts (limited by wire size == smoke).

1 Ohm would yield 5 amps.

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

Lol...I think you know what I meant...but fixed for accuracy.

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2006 Liberty CRD Limited

Provent @ 43,000 km
SEGR in progress
SAMCO Sport hoses @ 48500 km
Goodyear Wrangler Duratrac LT225/75R16

By way of follow up, thank you for the helpful suggestions. I had a curious find though...

When I installed 1, 2200 ohm resistor the light persisted.

When I installed 2, 2200 ohm resistors the light went out. The resistors are installed in parallel, so I think it's a resistance value issue. Perhaps the computer is looking for a number around 1000 ohms.

YMMV

If by 'same place, same contact' you are saying they are installed in parallel, then the effective resistance is 1/2 of 2.2k, or 1.1K Ohms.

If the resistors are too hot, you might swing by Radio Shack and get higher wattage resistors (bigger physically) - take it up a few steps if you can. It's close enough in impedance to a standard 1k resistor that I'd go with that - easier to find 'em and you don't need to install two in parallel.

FYI - Mark

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

Ugh, sorry for the bonehead mistake. How quickly one forgets intro circuits when allowed to, fluid flow always made much more sense to me I usually had to relate circuits to piping systems. Yes, the two resistors are in parallel, which seems to have worked.

Oh and I meant the external air temp was hot...Louisiana summers, not the resistors haha.

Thanks for the help.

Yea, the plumbing thing helped me too! ; ' )

Glad it's workin.

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban