For Sale LS Gen 2 DATC w/ heated and cooled seats

unclemuck

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DATC for Gen 2
Heated / cooled seats control
Silver color
Believe it was pulled from a 2005
Decent shape, but not immaculate. Taking pictures, it’s really just a couple very light discolorations on the bottom left and right edges, and a faint couple scratches on the glass.
Just looking to recoup my cost.

$50 shipped (US)

Tested and works; was hoping to solve the ole 1268 code after already replacing the DCCV with new Motorcraft part and the circuit testing OK. Looking like a DOA DCCV...

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joegr

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Interesting.
B1268 is not listed in the service manual. In general, 1268 refers to an issue with the defrost door and has nothing at all to do with the DCCV or temperature control.

If you really mean B1265, then that code is Cold Air Bypass Door Actuator Circuit Failure. The 2nd gen has no cold air bypass door, so that is an invalid code. The 2006 service manual says "Invalid code. Vehicle not equipped with cold air bypass door actuator. Ignore this code and continue diagnostics." Interestingly, by 2006 they had fixed the firmware so that it no longer reports this. My 2004 did, and the 2004 service manual had troubleshooting steps for it. It was impossible to carry out, since the wires, actuator, and door were all missing.

What actual operational problem are you having?
 

unclemuck

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Interesting.
B1268 is not listed in the service manual. In general, 1268 refers to an issue with the defrost door and has nothing at all to do with the DCCV or temperature control.

If you really mean B1265, then that code is Cold Air Bypass Door Actuator Circuit Failure. The 2nd gen has no cold air bypass door, so that is an invalid code. The 2006 service manual says "Invalid code. Vehicle not equipped with cold air bypass door actuator. Ignore this code and continue diagnostics." Interestingly, by 2006 they had fixed the firmware so that it no longer reports this. My 2004 did, and the 2004 service manual had troubleshooting steps for it. It was impossible to carry out, since the wires, actuator, and door were all missing.

What actual operational problem are you having?


Apologies - heat is getting to my brain. DATC code 2798.
Also get the 1265, but I know that is to be ignored.
Hah, that is interesting about the troubleshooting steps.

Longer story time:
Never had AC since I bought the car, always only full hot. DATC showed 2798 & 1265.
Also slight leak coolant at the typical housing spot, and the DCCV looked tired, but never had an issue with overheating.
Last winter, picked up new DCCV, thermostat, housing, gaskets, etc - just about everything aside from the hoses and degas. Finally replaced all that sometime over the winter. Bled by the book. Still no AC, still 2798. Didn't care much about the A/C at the time, was more concerned about the leaking coolant, so put off the rest of the troubleshoot until more time and above freezing temps were to be had.

Now, back at it again, trying to figure her out. Have gone by the manual for diagnostics, but am just surprised that I would have got a DOA OEM Motorcraft part.
Have tested resistance of the coils (~16 ohms IIRC).
The circuit back to the DATC doesn't show as grounded out; i.e.: resistance to ground > 10M ohms, didn't register on my multimeter.
I get 12v on the middle contact.
Connector checks out and is seated correctly.
Somewhat unrelated, but compressor is working, system gets cold, the refrigerant line sweats, Forscan shows me around 0*C post evap temp.
Coolant lines coming out of DCCV are warm, it's clearly not operating correctly, air from vents feels like very heated cool air.
Couldn't find any expected temps in the manual to look for sensor discrepancies, but no data looks clamped or like garbage.
To me it was worth the shot of replacing the DATC vs the DCCV again. Well, wasn't that.

Just reaaaally don't want to have to pull out the DCCV and buy another one if I'm not 100% certain that's the issue.

Bought and shipped Amazon, stamped Bosch, etc - It's genuine. But something tells me I won't be getting the 24 month warranty..
 

joegr

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So, if both DCCV coils are reading the correct resistance, why do you think that it is the problem.
You've eliminated the DATC via substitution. You have an electrical code, so no point is looking for mechanical issues yet.
You have only the wiring between the DCCV and the DATC left as the possible and now probable problem. That wiring is easy enough to test.
 

unclemuck

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I've checked those circuits multiple times, and just now again;
Pinpoint test H10, >10k ohms:
C1034-1 = ~1.2M ohms
C1034-3 = ~1.5M ohms

Which directed me to swap the DATC.

Happy to oblige if you have any other ideas for things to test, I'm just at a loss here for where to go, other than replacing the DATC or DCCV again. I do have Forscan if sensor readings would be helpful. I'll go test DATC-C228b against the table in the manual just for completeness.
 

joegr

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With the car running, DATC set to auto and min temperature, and the DCCV connected, check voltage between ground (bare metal of the car) and each of the three pins of the DCCV at the DCCV. You will have to stick a pin in each wire just above the DCCV connector to do this (repair the pin hole afterwards). The center pin should be really close to battery voltage, and the outer two pins should be really close to zero. Whichever reading is wrong, is the circuit (wire or connector) that is bad. Trace it back to find the fault location. This test is invalid if the DCCV is not connected (it is needed as a load).
 

unclemuck

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OK, that seems to be getting me closer.. reading battery voltage on BN/GN right before the connector, BN/BU was ~150 mV, so the code is right. Any tips on where to look for a fault as I trace it back? Not super easy to see given the snaking and loom..
 

joegr

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I'll have to grab the electrical diagrams tonight and see where you can best next grab that Brown/green wire to check it to find where the break is.
For now, I can say from memory that it next runs through another connector just above the DCCV. That connector also has the aux pump connections.
 

unclemuck

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That would be excellent, thanks. I’ll see what I can find. Yep, right above the DCCV, I’m familiar with that connector, will work back from there. Appreciate the help, Joe.
 

unclemuck

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Doesn't appear to be any of those connectors close by the DCCV, unfortunately. I see where the harness runs in front of the radiator, and up over the driver's side fender. Doesn't appear to be any easy access aside from cutting into the loom. Not seeing anything out of the ordinary there. Wondering if it might end up being easier to run a new wire. Though, if the harness is rubbing somewhere, I'd rather fix that. Now, if it's only the driver's side wire that's compromised, shouldn't the passenger side still get cold air? They're both hot... Maybe the hot air just vastly overpowers the cold?
 

joegr

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The driver's side core is bigger than the passenger side core. With the driver's side at full flow (full heat) that is enough to overpower the cooling on the passenger side.

Sadly, when I got home I couldn't find the wiring diagrams. At that point I realized that I had left them in my office when I was helping someone else. Unfortunately, I won't be back to my office before Monday...
 

unclemuck

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Heh, that’s ok, thanks Joe. I’ve got some time, so I’ll probably just try running a new wire today (unless you think there’s a reason not to, if it connects to something else along the way). Tracing that harness leads me to believe the break is likely going to be somewhere really unpleasant to get to. Would still be interested in the schematics when they’re handy though.
 

unclemuck

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Well, got a new wire run, but that didn’t work. Same 2798 with new 2797. It must go into something else, and is now picking up the original ground and now an open circuit from being snipped. Suppose I’ll wait for the wiring diagrams before going any further.
 

unclemuck

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Not sure if this is accurate, but found this schematic without much model info. If it doesn’t actually go through any other modules, I’m even more confused how it can be both shorted to ground and an open circuit...

4AC4EA53-B907-47A0-A2C0-AB9016642C36.jpeg
 

joegr

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Sorry, I did forget about this.
Yes, that page is correct.
It's not magic. If you have the correct voltage at one end of the wire (DATC end), and don't have that same voltage at the other end, then there is a break somewhere that needs to be corrected. The key is to measure the voltages at both ends with it in the max cooling state, with everything connected.
C264 is the other connector that those signals pass through. It should be under the dash, to the right of the glove box (may have to remove the glove box and/or passenger floor heater duct to get to it).
 

unclemuck

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No worries;
Sure seems like more magic than not sometimes... I’m familiar with electronics, I don’t understand why it’s giving me both the code for short to ground and the code for open circuit, it can’t be both. This is after running a new wire from the DATC to C134 that replaces brown/green, the wire for driver’s side, where the codes are indicating.

If it’s not raining for a bit, I’ll go back out and re-test...
 

unclemuck

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Update:
So, I've verified the DCCV is functional - When I ground out each of the wires, I can hear the solenoids closing, and had someone sit in the car, and the temperature goes go down. Not all the way to 'cold' - possibly a low refrigerant issue as well, I haven't checked that yet, but not heated.
Forscan shows the DCCV driver's status as always '0', while passenger's side has actual values.
I'm thinking I just got lucky enough to have bought a second DATC with the same issue.
Further, when I swapped the driver and passenger solenoid wires in the back of the connector to the DATC, it still gives me 2798. If the DATC was functioning correctly, and it was actually a short to ground on that circuit to the DCCV, I would expect to see the relevant code for the passenger's side.
Also, if it was a short to ground, I would expect to get NO heat on that side, as the solenoid would be closed with a working DCCV. Unless the micro-controller in the DATC is doing something fancy when it detects an issue.

I've studied each of the DATC boards closely, tested some of the components with a multimeter, and looked up the datasheets for some of the chips to better understand what's going on in the signal path; I found no evidence of burned traces (although there is some discoloration on some of the pads, but nothing crazy). I even replaced the driver's circuit's low-side power switch on one board with the passenger side from the other, thinking the chip possibly self-destructed in a high-current situation, but still the same result. There is definitely something shorted on the driver's circuits inside the DATC, evidenced by the 15k resistor next to the low-side power switch not measuring correctly - yet when it's pulled off the board, it's fine. So there is a lower-resistance path to ground on the board... somewhere.... but I can't pinpoint it. Must be something internal to a chip, or that can't be easily seen.

I think the best next course of action is to try and source another DATC that I can confirm working in another vehicle first.
 

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