AW70: overdrive off light always on

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Sakari Ailus - 14 Oct 2006 21:01 GMT

Hello,

I have a 1990 Volvo 240 with AW70. I've owned the car since last
summer and today I was replacing some of the last failed bulbs which
had been in that state already when I bought the car.

I was slightly surprised to find that the "overdrive off" indicator
light on the metre console is always lit iff the engine is running (as
far as I remember, I'll have to ascertain this). The "overdrive off"
indicator flickers when the engine is idling but the flicker quickly
vanishes when acceleration pedal is pressed.

Yet overdrive still works fine, including the button for enabling or
disabling it. I'm pretty sure of this since the effect of disabling
overdrive at 100 km/h (about 62 mph) is very noticeable. Whether
overdrive is enabled or disabled does not seem to have any effect on
the indicator.

So, my question is: is someone able to guess what could cause the
described symptom? Obviously it's not the famous oxidised fuse
contacts since that would prevent overdrive from working altogether.

Regards,

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Sakari Ailus
http://www.iki.fi/~sailus/

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Mike F - 16 Oct 2006 13:37 GMT

> Hello,
>
[quoted text clipped - 23 lines]
> Sakari Ailus
> http://www.iki.fi/~sailus/

There's a yellow-red wire that goes from the overdrive relay to a
connection right beside the light. I'd have a look at how you
reinstalled that on the cluster.

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Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

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Sakari Ailus - 16 Oct 2006 19:04 GMT

> There's a yellow-red wire that goes from the overdrive relay to a
> connection right beside the light. I'd have a look at how you
> reinstalled that on the cluster.

Hm. I actually didn't disconnect any wires when changing the bulbs.
But someone else has done it in the past --- the speedometer has been
replaced 67 000 km ago. I'll check the colour of that wire. And maybe
also the wires connected to the overdrive relay.

Thanks.

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Sakari Ailus
http://www.iki.fi/~sailus/

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James Sweet - 17 Oct 2006 03:39 GMT

>> There's a yellow-red wire that goes from the overdrive relay to a
>> connection right beside the light. I'd have a look at how you
[quoted text clipped - 6 lines]
>
> Thanks.

Is the overdrive working? It's possible the relay failed by conincidence.

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Sakari Ailus - 17 Oct 2006 19:43 GMT

> Is the overdrive working? It's possible the relay failed by conincidence.

Yes. So the problem is that the indicator doesn't work correctly. :]

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Sakari Ailus
http://www.iki.fi/~sailus/

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James Sweet - 17 Oct 2006 20:45 GMT

>> Is the overdrive working? It's possible the relay failed by conincidence.
>
> Yes. So the problem is that the indicator doesn't work correctly. :]

It still wouldn't hurt to try tapping the relay or resoldering it, as I
recall the indicator wires straight to that. Another possibility is that
the wiring harness behind the instrument cluster has chafed on something.

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Sakari Ailus - 19 Oct 2006 21:30 GMT

> Hm. I actually didn't disconnect any wires when changing the bulbs.
> But someone else has done it in the past --- the speedometer has been
> replaced 67 000 km ago. I'll check the colour of that wire. And maybe
> also the wires connected to the overdrive relay.

Overdrive relay is fine --- I checked it with a multimeter. But it
appears that the rpm meter wire (red-white) had been connected to
overdrive indicator. Interesting wiring choice from the earlier
owner... ;-)

Thanks to everyone for help.

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Sakari Ailus
http://www.iki.fi/~sailus/

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