Code help! Had a quick search through and found a list of codes, and mines not on it!
Anyone any idea what a code P1511 is?

2002 Liberty (Cherokee here in the UK) 2.5 CRD.
Apparently the 2.8 is the same engine 'bored out' to 2.8.

Ok found it, i think!
Code p1511 ; "battery sense line 1 voltage too low/high"
and its cold here at the moment in the uk and it was struggling to start. So alternator or battery? Any quick way of diagnosing either?

I cannot find that code in any of my 2005 or 2006 CRD documentation. You might try Sir Sams NOOB guide links to various manuals which includes export models and the 2.5L engine.

That said I'll assume what you found is correct and say it could be either. Over here most any parts store can load test the battery and check alternator output don't know about your side of the pond. Is your battery close to the end of the warranty period? If so I'd bet on a bad battery as nothing kills a weak battery quicker than very low or very high temps, if you have a charger try putting a good charge on it and immediately after removing the starter try cranking the engine; if it cranks better you likely need a new battery. If your alternator has the "clutch" like ours does it show any red dust or does the belt/clutch wobble when the engine is running; if so your alternator is on the way out and at least that clutch needs replacing.

If you have access to a loaner battery with good cold cranking amps you might try dropping it in long enough for a cold start to see if that improves things. Unfortunately improvement won't tell you anything more than you either have a weak battery or a weak battery charge due to a bad alternator.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

Cheers for the reply, think it's the right code, someone had the same over on jeep forum. Looks like the only way of knowing which is the multimeter test. Or would the jeep throw a code if the alternators faulty?
Makes sense if it can detect battery voltage coming in and report it's too low, surely it could detect output voltage from the alternator and tell if that's too low?

Symptom List:
P1511-BATTERY SENSE LINE 1 VOLTAGE TOO HIGH
P1511-BATTERY SENSE LINE 1 VOLTAGE TOO LOW
P1512-BATTERY SENSE LINE 2 VOLTAGE TOO HIGH
P1512-BATTERY SENSE LINE 2 VOLTAGE TOO LOW
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P1511-BATTERY SENSE LINE 1
VOLTAGE TOO HIGH.
When Monitored and Set Condition:
P1511-BATTERY SENSE LINE 1 VOLTAGE TOO HIGH
When Monitored: With the ignition on or the engine running.
Set Condition: The ECM detects Battery Sense circuit voltage above 17.50 volts.
P1511-BATTERY SENSE LINE 1 VOLTAGE TOO LOW
When Monitored: With the ignition on or the engine running.
Set Condition: The ECM detects Battery Sense circuit voltage below 7.98 volts.
P1512-BATTERY SENSE LINE 2 VOLTAGE TOO HIGH
When Monitored: With the ignition on or the engine running.
Set Condition: The ECM detects Battery Sense circuit voltage above 17.50 volts.
P1512-BATTERY SENSE LINE 2 VOLTAGE TOO LOW
When Monitored: With the ignition on or the engine running.
Set Condition: The ECM detects Battery Sense circuit voltage below 7.98 volts.


There is a whole bunch of diag after the above, but a low battery will cause this code.

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Resurrected 2005 Liberty Sport CRD
Canadian DRL mod

CRD Motor/Timing Pics
http://www.flickr.com/photos/68442076@N02/sets/72157629389449367/

The alternator output is connected to the battery positive via a thick cable so effectively the voltage is the same. It actualy connects via a "fusable link" according to the circuit diagram. You will not get any other code for a faulty alternator...the ECU only knows there is a problem if it tries to lower or raise the voltage and does not get the right correction.

The ECU actually picks up the sensing of the battery output via a fairly thin wire that goes through fuse 26 and fuse 6 in the Power Distribution Center (PDC) and then finds its way to the ignition switch so it has a few areas where it can fail.
The ECU only measures "Line 1" as stated in the detailed error code post above...Line 2 is the Battery Temperature Sensor which I mentioned in my reply to your post on jeepforums
This CRD Forum here on Lost is actually the best place to be for any CRD problems.....as stated here...start with the battery as the main culprit

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2002 Export CRD 2.5 Sport

Voltage tests show >13.5 across the battery with the engine running so looks like the alternator is doing its stuff. Ordered a new battery today should be here tomorrow. I'm afraid the redtop ones were ridiculous at nearly £200! Varta silver got the job at £105.

As long as the battery fits and the cold cranking amp rating is on the order of 800 it should do although you do need to stick to maintenance free (e.g. sealed) batteries. I'm fond of my Sears Platnium P1, pricey but an excellent warranty, but stoutdog went with an Interstate for $70 less with almost as good a warranty. The chat is the current generation of red tops are not as good as they used to be.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs