Alfa Pages

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

I have 14v on the 2 wires when i take them off the connector, as soon as i connect it to the connectors i get nothing. If i leave one wire connected and check the voltage on the wire not connected i get 5v. I have squeezed the connectors together to get a better bite and put them on and off several times.

Any ideas??
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

eagle3 · Alfa 33 Joined: 11 Nov 2007 Posts: 402 Location: France

Bad earth?
_________________
Alfa33 QO 1984
Alfa33 1.3i.e. 1994

Oggie · Posted: Sun Jan 03, 2010 9:57 pm Post subject:

It will probably be the damed connector block under the dash, the same one you had trouble with I think before with your fans, I have had this and bypassing the block solved it.
_________________
PHAT 33

33bits · Posted: Sun Jan 03, 2010 9:59 pm Post subject:

Iain just wrote what i was thinking.
_________________
155 sportpack
33 16v Sportwagon
33 Permanent 4
33 16v (for sale)
156 JTS sportwagon
contact me for any 33 parts. Alex, 07896-327708

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

Ok, thanks guys but I don't get it, can you elaborate a little.
There is voltage on the connectors to the rear de-mister when they are not connected to the rear de-mister connections.

Thanks Alan
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

eagle3 · Alfa 33 Joined: 11 Nov 2007 Posts: 402 Location: France

Can you be a bit more specific about which connectors you're talking about?
_________________
Alfa33 QO 1984
Alfa33 1.3i.e. 1994

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

I'll try

On the rear window there are 2 copperish male spade connectors either side of the heating element. There are 2 black wires that connect to these spade connectors. If I take the wires off the spade connectors and test for voltage I get 14v “engine running on tick over, battery charging.” When I connect one of the wires to a spade and put the DMM on it and then connect the DMM to the other wire “not connected to the spade on the heating element” I get 5v. As soon as I connect both wires up to the spade connector and test with the DMM on the spade connectors I get 0v.
Hope that makes sense.
Thanks in advance
Alan
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

eagle3 · Alfa 33 Joined: 11 Nov 2007 Posts: 402 Location: France

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

lol, ok
now listen very carefully, i will say this only once, not Laughing

Yes to what you have said, with the hatch open, i put the DMM on the spade connectors that are part of the HRW matrix and i get 0v.
If i take off both black wires that connect to the matrix and stick my DMM into both of these connectors i get 14v, so power is getting there.
If i connect 1 of these wires to the HRW matrix spade connector and put one of the probes of my DMM on that and then connect the other probe from the DMM to the wire on other side but not connected to the HRW i get 5v.
Fingers crossed i made sence this time lol.
Thaks
Alan
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

Oggie · Posted: Mon Jan 04, 2010 7:43 pm Post subject:

DDM (digital multi-meter)
HRW (heated rear window)

Al its the connector i tell Ya, I had exactly the same symptoms as your meter reads,cut, solder and insulate the power cable to the window heater as the old plastic cannie handle it anymore captain!!!.
_________________
PHAT 33

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

ok....

dont forget i have a ser 3, different wiring??
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

Oggie · Posted: Mon Jan 04, 2010 8:35 pm Post subject:

You know what Im gonna say so, Its just a positive cable to a fuse then to the connector then off to the switch, an earth on the boot lid, the wiring is the same as an s2 , you may have different colour cable and switch and connector but the principle is still the same, put aside your ddm for now and look for a bad connector al, its in there somewhere I would lay a whole £1 bet on it Laughing

_________________
PHAT 33

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

lol place bets now Laughing

I'll do my best, i hate electrics.
Cheers

Guest · Posted: Tue Jan 05, 2010 9:21 am Post subject:

I agree, there's a poor connection somewhere. You measure voltage on the wires when they're disconnected, but this is voltage is all bark and no bite. Due to a (big surprise in an old Alfa) poor connection somewhere creating high resistance, the voltage is unable to drive enough current through the circuit to get your demister very warm.

The poor connection might be a 'bad earth' - one of the two wires you've mentioned earths the demister to the metal of the hatch, and the connection to the hatch could've corroded. To work out which is the earth wire (assuming you can't just trace it and see), unplug both wires, turn the demister switch on and use the DMM to measure between wire 1 and any exposed/unpainted bit of metal on the car body, then between wire 2 and the exposed bit of metal. The wire where you measure 0V is the earth for the demister, and the wire where you measure 12~14V is the one supplying the demister with power.
Turn the demister switch off, change the DMM to the ohms / resistance setting, and measure between the earth wire and your exposed bit of metal. You should measure only a couple of ohms (say between 0 and 2 ohms). If you measure much more than this, you've got a bad earth. Trace wire to where it attaches to the hatch, undo the connection and clean it. After you've confirmed with the DMM that the earth's good, set the DMM back to the volts setting. If there are no problems with your demister circuit, you should measure most of the battery voltage being dropped across the demister (i.e. 12V or more between the spade connectors when the wires are connected and the switch is on).

If you don't have a bad earth, your poor connection is somewhere else e.g. the wiring loom connector plug that Oggie is betting one pound on!

Ben_nz · Posted: Tue Jan 05, 2010 9:23 am Post subject:

Oops, that was me above. I wasn't logged in and now I can't go back and edit out all my typos. Crying or Very sad

_________________
"Now, all that is left to do ... is wait that something else brokens, to fix up again!"

eagle3 · Alfa 33 Joined: 11 Nov 2007 Posts: 402 Location: France

Isn't the left spade +(12v/14v) and the right spade - (bodywork)?
_________________
Alfa33 QO 1984
Alfa33 1.3i.e. 1994

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

Thanks guys, eagle you are correct, i got -14v at first, then swapped so the + was on the left side.
When i can move my car i will investigate further. I will connect teh + to the demister and the other side to an earth on the body. Where is the earthe from the demister btw?
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

eagle3 · Alfa 33 Joined: 11 Nov 2007 Posts: 402 Location: France

_________________
Alfa33 QO 1984
Alfa33 1.3i.e. 1994

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

Thanks eagle,
Come to think of it a while back i took those rubber things off and turned them around, the earth could have come off
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

eagle3 · Alfa 33 Joined: 11 Nov 2007 Posts: 402 Location: France

AhA!

_________________
Alfa33 QO 1984
Alfa33 1.3i.e. 1994

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

well, the ones i took off were on the body. I checked the earth which is a 10mm bolt on the tail gate near the earth cable connection to the RWH and used a good earth from the boot light, made no difference.
Sad

_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

Anyone?
If i have eliminated the earth, that leaves the + part of the circuit or the element?
_________________
x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

Oggie · Posted: Thu Jan 14, 2010 12:20 pm Post subject:

melted connector block!!!!!!.
_________________
PHAT 33

john 33_16v · Posted: Thu Jan 14, 2010 12:23 pm Post subject:

You could run a good 12v supply from the battery or a spare battery direct to the element to eliminate that.

John
_________________
If it aint broke, fiddle with it until it is!
- - - - - - - - - - - - - -
93 33 16v Mirtle Met
08 Fiat Grande Punto Exotica Red
90 Yamaha FZR600 Genesis- Silky white/red/blue

lee16v · Posted: Thu Jan 14, 2010 1:52 pm Post subject:

I think Iain is trying to get a message to you Al! Laughing