OK, I am stumped a tad, and confused also.

I have read all I am going to read re this heater tap/valve fiasco, and put this out there for consideration. I have JTIS, but none of us can get it work on my W8 system, it constantly states "Windows cannot open the program", so enough is enough for me.

Common sense will sort this thing with a little help.

The Black S has no heat, nor has the Silver one.

Best diagnosis is the tap/s are toast, as per my reading on here, and elsewhere just to get my head around this thing.

New tap arrived, one only at the price we pay down here, so the fun began, and 2 hours later the old tap is out. This is worse than any task I have ever done on any Jag, V12's included.

Looks fine, and OHMS out exactly the same as the new one, bugga. Made some test leads, and with +ve applied to the centre pin, and -ve to the outer pin/s, the tap solenoid/s close 100%, bugga again. New tap is the same.

OK, blocked heater core, NO, blows thru sweet both ways.

When I disconnected the 3 hoses from the quick connect couplings, the 2 going TO the core had COLD coolant run out, the lower 3rd was HOTtish, as I had run the car about 2 hours prior. The hottish sounds about OK, as it is a direct coupling to the lower hose of the water pump, eventually, and the engine coolant was still about that temp.

Sooo, based on this it appears that the "system" is applying an earth track to both solenoids, thus closing them, and NO flow. This is the scenario when COLD is needed. I have the temp set at 23C, and NO heat. An ambient sensor somewhere????, dunno.

I know I will have to test the activity at the plug with the meters, but that will be tomorrow, its dark and cold out there now. I understand 12v at the centre pin, and the ECU supplies an earth to close the taps, and if that is present at 23C I have other electrical issues.

Any suggestions, even vaguely related, would be nice.

Failing that, I will leave the tap unplugged electrically, that way the solenoids will default to OPEN, and I should have heat. YES?????.

I also understand a myriad of gremlins can be behind the dash, but that is waaaaay out of my league, unless someone has a SIMPLE item that causes this grief.

Thanks in advance.

 

You should see a varying voltage on the non-centre pin that heads towards ground the hotter heat you select. I'd choose max heat when testing.

What you do next depends critically on what voltage(s) you get...

 

Thanks JagV8, that is soooooo helpful.

 

It may be a PWM signal in which case your meter may be unhappy. Try AC volts instead of DC volts if so.

 

Sometimes there is an offset between the in cabin temperature sensor and the climate control panel.

23*C may not be enough to command heat during testing, try 28*C for testing purposes.

The offset bothers some people, I just crank the temperature higher.

 

May well be dirty sensor(s) that cause the offset.

 

OK guys.

All back in one piece.

With the tap electrically unplugged, we have heat, as expected.

The centre terminal of the plug (unplugged) is battery volts at ALL times, which I find bizzare, but I will look at the wiring diagrams I have later tonight, to observe the supply chain for this terminal.

With the meter Red in the centre post, and the meter Black in the outer terminal I have ZERO volts, no matter where the demand in the cabin is set.

I tried the AC section of the meter as well, no change.

I did the same electrical test on her car (the Silver one), and the same result. Also hers has heat with the tap unplugged electrically, so at the moment she is "happy".

 

Most things on the car are live and then that feed is switched to ground. Easier electronics. True for the bulbs and stuff, too, same reason.

Zero is either genuinely zero (not connected, probably) or a PWM signal your meter can't interpret. A DCCV that is OK but isn't varying the heat would mean it's not getting a signal, whereas you wouldn't know whether it's got signal or not with a non-working DCCV. If you know the DCCV is OK then you're looking for a wiring fault or module fault or perhaps a fuse/relay. Electrical Guide is next point of call.

The later (2002.5MY-on) cars suffer from burnt tracks in the module caused by a DCCV gone bad but I think we've not heard of this on the early cars. Only way to know is to work through fuses/relays/wiring/module.

 

Thanks for that JagV8.

Update today.

Spouse got involved, and sitting in the passengers seat doing whatever spouses do in cars, and under her threat aimed at the S, of being replaced with a BentleyR, I proceded with the following.

Replugged the DCCV, and cranked the temp to HI, and fired the beast, and waited, GOT HEAT, damn, so turned the temp down to 26C and the heat reduced, then to 20C and much cooler. Outside temp about 13C.

I then used ALL the various buttons along the lower control panel for air distribution, and lots of "noises" and "buzzing", and air began coming from the selected vents, made me think that maybe I had a jammed flap????, or something similar.

I think maybe the incar temp sniffer is clogged, as I simply dont remember cleaning this one. I remember doing the Silver one, and the X300, so now on the top of the to do list.

Felt the pipes in the engine bay, all 3 HOT, never been this way before, so maybe the old tap is suspect.

Soooooo, plugged the old tap into the loom plug, and observed the operation of the plungers, and it seemed to perform as I expected it would, so still not convinced.

I like the old Rover. If you want heat you open the LH bonnet panel, turn the tap located on the thermo housing to ON, HOT water flows, and you got heat, how simple it used to be.

I have modified the heater tap mounting bracket to make refitted this item MUCH easier, and will post the snaps etc in a seperate thread to avoid off tracking this thread.

Thanks for ALL the quick replies to assist me.

 

Man that Bentley R sounds sweet! Are you sure you don't want to upgrade??

You really can't rely on the DCCV if it's not been replaced. It's a wear item just swap it out.

Many people have screwed around with cleaning and lubricating the solenoids or even just exercising them by running the temperature setting from max hot to max cold and back which will cycle the DCCV valves open and closed. These are all short term repairs if they work at all.

If you continue running a bad DCCV you will take out your CCM or RCCM because the solenoids start drawing more and more power and the climate control board has no over power protection.

So you draw more and more amps until the board is toast. Now this is not a total disaster because they are repairable and even shade tree mechanics can and have fixed them before.

If you are really interested you need to measure the current draw on each side of the DCCV. Checking the voltage won't tell you anything.

I am still unclear.

1. Have you swapped the DCCV out for a new one? You mention a new one but did you install it and is it in the car right now?

2. If you did and still have problems have you pulled the CCM or RCCM (Depends if you have navigation or not) and inspected the board for burned traces. Yes they will be visible.
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Tbird,

Yep. after the mammoth effort to get the old one out, and 1 bottle of JD consumed in the process, putting the old one back just was not in the equation.

The old one is the original, so 14 years old, and at 90000kms, has seen NO use as such.

Coolant is good. Car has had dealer servicing, although based on kms, not time elapsed, so iffy at best.

It is all working fine, got a real test yesterday, and "her" feet were warm, so I am back out of the doghouse. Just got her car to do now.

I will sort an amp draw test just for interest sake.

The Bentley R is AWESOME. Made the fatal, and drove it, DAMN. He is looking at the 3 Jags for the Bentley, so temptation is HIGH. Then I watched the fuel gauge move faster than the PreHE V12 fuel gauge, so emotion got stomped on, and reality kicked in. I reckon the Jags are safe for now.

 

Amp draw done.

NEW tap fitted to the Black car, 0.79amps each solenoid.

Old Black car tap, 0.80 amps each solenoid.

Silver car tap (original I think?) is 0.80 amps per solenoid.

Only noticeable difference is the "audible click" is identical on the Black new, and Black old tap, and the Silver tap is barely audible, so maybe that tap has an issue. More investigating tomorrow when not so cold and miserable.

The heat etc in the Black car is superb, and I reckon my brain needed some retraining as to how this system actually works. The XJ-S, X300, S2 etc all give that blast of HOT air as the system starts off, and then it settles into what it does, whereas my understanding now is the S kind of creeps up on you with that wafting type of heat that gradually warms the car, and YES I have only had 1 drink thus far, as I have taken spouse out for tea, and I was the driver.

 

Update.

Finally got ear bashed enough to replace the heater tap on the Silver S, AKA, hers.

Found that there was NO 12v live to the centre of the 3 wires in the plug, mmmm, not much in the handbook about that, so waded thru the wiring diagrams, and found that the 12v live is supplied via fuse #1 of teh engine bay fuse box, which was blown, mmm again.

Replaced the fuse, got 12v live, goodo.

Removed the tap, jammed solid ay about 10% open, could barely blow thru it.

Blew thru the heater core, coz I could, no blockages evident.

Swapped the hoses, and fitted the new tap.

Now it has heat as designed, and SHE is happy, and I am off the hook for an hour or 2 maybe.

 

Time to break out the second bottle of JD then?

 

Maaaaate.

That was BEFORE I opened the bonnet.

Metho came in for the bloodied knuckles, OUCH.

Next time will be SIMPLE, as I fitted standard hose clamps, and that extra slotted bracket will have it out in under 10 minutes. Not being pessimistic, but there WILL be a next time.