THE ROVER SD1 FORUM

Adam Adamant Lonsdale

Hi all, hopefully someone else may have had expeirience with this problem. My 1984 SD1 3500SE is experiencing a problem that is irritating. My heated rear window will switch on fine from when the car starts, however, as it warms up (the car that is) the heated window switches itself off and won't come back on again until the car stops and cools down. To make it more confusing, if the switch is left on, after I turn off the ignition, the light on the dash suddenly comes on for a few seconds.

Normally I can switch it off and on as I please. Some people are saying the relay might be faulty. Any ideas?

Also, can I confirm it's the relay that's located behind the fuse box in the boot?

_________________
1984 Rover SD1 3500SE
Arum White Automatic
Reg: ROVRV8

ramon alban · Last edited by ramon alban on Fri Nov 02, 2007 4:47 pm; edited 1 time in total

Adam Adamant Lonsdale wrote:

Hi all, hopefully someone else may have had expeirience with this problem. My 1984 SD1 3500SE is experiencing a problem that is irritating. My heated rear window will switch on fine from when the car starts, however, as it warms up (the car that is) the heated window switches itself off and won't come back on again until the car stops and cools down. To make it more confusing, if the switch is left on, after I turn off the ignition, the light on the dash suddenly comes on for a few seconds.

Normally I can switch it off and on as I please. Some people are saying the relay might be faulty. Any ideas?

Also, can I confirm it's the relay that's located behind the fuse box in the boot?

Adam,

If the car has aircon, the heated rear screen is disabled when the big aircon fans kick in to protect the charging/battery system from overload.

Study the two cct diagrams here to see how.

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Those same fans if fitted, are also used to cool the engine under extreme hot conditions by a rad stat thus the rear screen heater is disabled again.

The timer cct for the heater is inside that tall looking relay and can get corroded contacts. If so, remove it, open it up and inspect/clean the moving parts.

Because of the way the relay is constructed it can also develop dry soldered joints where the spade connectors join to the cct board, resoldering them is easy,

The reason the light comes on on the dash could be that the relay/timer is just resetting itself.

Edited to add second cct diag

_________________
Ramon

Adam Adamant Lonsdale · Posted: Fri Nov 02, 2007 2:15 pm Post subject:

Hi Ramon,

Thanks very much for the reply. You must forgive me, I am not mechanically minded when it comes to these matters. After studying the diagram I now know I definately know nothing about the electrical systems of my Rover.

Yes, there is air con in the car (I think most Australian spec models had it as standard), so the possiblity is there on part of it cutting out when reaching that certain temp. The trouble is that my car just had a brand new Rover V8 Engine installed and since then the temp gauge shows it as steady at the 100 mark, so essentially the car will run hot no matter if air con is on (even here in the Australian winter) or not, but I will try it tommorow morning without the air con on.

When talking about the "tall looking relay" is that the one housed behind the fusebox in the boot or the one under the passenger side dash? Would it make sense to just replace it with a new one or good second hand one? I am off to a Rover wreckers tomorrow morning so I could pick one up there.

I hope you don't find this reply in anyway offensive, as mentioned above most of the mechanical side is completely lost on me (I normally let my mechanic worry about these matters). You seem to know your stuff, I'll definatley like to pick your brains on other details too!

Oh by the way, here's a picture of my beloved...

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_________________
1984 Rover SD1 3500SE
Arum White Automatic
Reg: ROVRV8

Chris P · Posted: Fri Nov 02, 2007 2:59 pm Post subject:

Adam Adamant Lonsdale wrote:

new Rover V8 Engine installed and since then the temp gauge shows it as steady at the 100 mark, so essentially the car will run hot no matter if air con is on (even here in the Australian winter) or not, but I will try it tommorow morning without the air con on.

100C as shown on the dash? Don't rely on that, if you suspect the engine
is running hot, get it checked properly at a garage. The dash display is
not that accurate, and there were/are different gauges and senders for
different build years (there are other threads on this forum describing
the part differences in more detail).

I changed the sender on my Vitesse a while back - ever since, it's
shown 100C, previously it was the correct ~90C. The replacement
sender is an old one (and probably) intended for 50-130C gauges
(series 1, early series 2), not the later 60-140C.

Nice SD1 by the way, good to hear of them being appreciated so
far away!

ramon alban · Posted: Fri Nov 02, 2007 5:28 pm Post subject:

Adam Adamant Lonsdale wrote:

Hi Ramon,

Thanks very much for the reply. You must forgive me, I am not mechanically minded when it comes to these matters. After studying the diagram I now know I definately know nothing about the electrical systems of my Rover.

Yes, there is air con in the car (I think most Australian spec models had it as standard), so the possiblity is there on part of it cutting out when reaching that certain temp. The trouble is that my car just had a brand new Rover V8 Engine installed and since then the temp gauge shows it as steady at the 100 mark, so essentially the car will run hot no matter if air con is on (even here in the Australian winter) or not, but I will try it tommorow morning without the air con on.

When talking about the "tall looking relay" is that the one housed behind the fusebox in the boot or the one under the passenger side dash? Would it make sense to just replace it with a new one or good second hand one? I am off to a Rover wreckers tomorrow morning so I could pick one up there.

Hi Adam, No worries mate, I cut my career teeth as an electronis design engineer from '60 - '68 and spent the rest of my working life either testing components or shipping them around the world. Thus when I got into hobby SD1's in '93 the electrical bits fell easily into context but then I know b----r all about engine mechanics.

Its absolutely ages since I worked on the rear heated screen circuit but I'm sure the tall relay in the boot is the timer/heavy duty relay.

You are looking for items 240, 150 and 115 on the main cct diagram and associated index. The inline fuse is item 67 and the cct derives it power from pickup point M6 which is via the Aircon cct.

I have added that link to the earlier post.

_________________
Ramon

Adam Adamant Lonsdale · Posted: Sat Nov 10, 2007 10:53 am Post subject:

Hi all,

Thanks for all your help. I changed the relay and it is still doing it. However, summer is nearly here so it won't be needed for a while. When it goes for it's next service I'll ask my mechanic to take a look and see if he can work it out. However, there is now another problem with the cooling system..........I've posted in the engine area to see if anyone can offer advice.

_________________
1984 Rover SD1 3500SE
Arum White Automatic
Reg: ROVRV8