One note: The climate control module can get damaged BUT the only ones that have burned the trace out are the cars without NAV. If you have SAT/NAV the remote climate control box as described has never been damaged.

Don't know enough about the differences to understand why??
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Thats what I have read. So this leads to another question; I hooked a hot wire from the battery to the center term on my old valve and the using a test light grounded both the outside connectors - light lit but nothing happend in the valve and one of them had worked, or I would have had hot air on both sides, right? Makes me start wondering about the voltage, maybe it low?

 

you always have power on the center wire, (or should unless the fuse is blown, but that the same 1 for the ac clutch too. now if you ground the outer 2 this closes the valves. of course you may also have an issue with the evap temp sensor on the side of the case. If it goes bad the ac ecu this the evap is freezing and gives hot air. These are cheap so if you want to throw parts at it. I dont remember the values( I read them with IDS) but you can use a dvom, but Im at home and dont have the electrical diagrams and manuals memorized

 

This is an untrue statement. There have been many cases of SAT/NAV versions getting burned out. The SAT/NAV version is just as susceptible to damage as the non-SAT/NAV unit. There are absolutely no hardware differences [edit: as far as the heater valve control is concerned] between the two versions for the 2003-2008 model years.

 

true, and there are just no where near as many with nav, so the numbers are much smaller with blown ecu's. And i would venture a guess that maybe 1 in 5 have a damaged module as the result of the dccv valve shorting

 

You can't use a test light to perform the grounding of the outside connectors.

The reason:
Adding the test light's bulb in series with the circuit creates a voltage divider. The original circuit, +12V source -> Solenoid -> Gnd, now becomes +12V source -> Solenoid -> Bulb -> Gnd. Note that both the original and new circuits are 1st order differential resistor-inductor circuits which requires impedance calculations to describe accurately, but we'll just stick with using "resistance" here to keep to the point. In order for the solenoid to fully activate, it needs to see a certain potential difference (a.k.a. "voltage"). Let's assume that the solenoid needs 12V (or something close to 12V) to activate. In the original circuit, the solenoid sees all 12V from the source because it's just 12V on one end, and Gnd on the other end. In the new circuit, the bulb, which is a positive-temperature coefficient device, has reasonably low resistance when it's off, but suddenly increases resistance dramatically when it's turned on (i.e. 15 times more). The bulb, whose voltage across its terminals is 12V x [(bulb resistance) / (bulb resistance + solenoid resistance)], immediately takes away available voltage from what should otherwise have been made available to the solenoid only. Hence, the solenoid doesn't get the 12V it needs and does not activate. Ignoring the possible current variations in the new circuit, this voltage divider phenomenon will cause enough problems already.

The reason in layperson terms:
"The test light will eat up too much power to light itself up, so that the heater valve doesn't get enough juice to operate."

To check for operation of the valve, you need to either use a regular wire (i.e. alligator clip wire), or a use a multimeter set to measure current (fused 10A or so).

 

Yup.

 

Sorry I have never heard of a car with NAV burning up the remote climate control module. Can you point to anybody posting that this has happened?? The ONLY cars that have burned up the wire trace on the climate control module do not have NAV.
In fact there is not even any instructions for fixing the burned up wire trace for NAV based cars??
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The circuit diagrams appear very much the same so maybe it's just that the fairly few posts about damaged ACCMs have been non-nav? (Is it certain they all have been?)

 

Could be?? Does anyone have a picture of what burns up on a NAV equipped car?? It would be a help when looking for damage.
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As Brutal has mentioned, there are less NAV-equipped cars (i.e. S-Types) than non-NAV cars. Additionally, the number of people who are active on the forums is far less than the number of people who own the car. When a car problem arises, the majority of the owners out there will simply bring their car to the dealership or other mechanic's shop to get the problem resolved. Therefore, I wouldn't be surprised to find only limited anecdotal evidence (if any) of cases where NAV-equipped cars suffered the same fate.

Unfortunately, if there are not any posts by people with NAV-equipped cars, then there is nothing we can do about that. Either way, it doesn't make any difference to me because I have my own repair log that documents all the modules that have gone through my hands. The NAV version modules have represented roughly 10-20% of the occurrences.

I'd also be very wary of following any instructions online for fixing burned up wire traces. When this type of repair is done improperly, it can lead to much more problems down the line.

 

Here you go:


This is the most common sight, and is the first thing to look for. It has a pleasant, sweet smell.

There are other components that can be damaged as well, but those may not be apparent to the keen nose or naked eye (even mine).

 

So helpful when a PCB trace burns instead of the fuse

Nice pic, tho

 

Canon point & shoot macro power!

There were so many ways their design engineers could have done things differently to prevent this...design flaw, but they didn't.

 

MAn JC I almost fell out of my chair reading this. This is WHY you NEVER EVER want to use a test light on circuits involving modules. Your definition is text book on why not. Theyre low impedance, and amperage operating
circuits. useing a test light pulls too much current through an electronic module and lets the smoke out of a previously good unit....theyre not even good for checking light bulb circuits anymore since those too are a ground controlled circuits from lighting modules....Heck 2010+ cars have 30+ computers/modules on them last time I counted. And IM afraid to look at the new XJ.....even the fuse boxes are smart modules now days too...Oh and to think we used to have to CRANK the car to start it. And keep the lights filled with oil to light them....

 

I always reffer to those type of things as ENGINEERED POINTS OF FAILURE...its keeps the parts chain flowing. Just like all the plastic on the engine. They all seem to fail in the exact same spots......"hey lets makes this alittle thinner right here boys, why we can call it EPOF"
lol

 

Mmmm...I had been suspecting....

 

What part is this a picture of? Is it the engine control module?

 

This is a picture of the Climate Control Module circuit board.

 

Thank you very much for the picture!! That is really great trouble shooting!! But I have NAV and really need to know where to look on the remote climate control module. Or are you saying that the picture IS for the remote climate control module?
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