Dashboard lights 144DL

[Kirkie]

Having just bought my 144DL I have a few jobs to do.
My dash lights do not work. Mine is a 1972 with the strip speedo.
On reading the posts in the library it seems that the dimmer switch is the usual culprit in most cases. Evidently removing the knob destroys it.
Is it possible to connect the wires directly at the back of the rheostat so that there is just the brightest option.
I know its not the light switch as the clock light works when the sidelights are switched on..
Also, any tips please on the easiest way to access the rear of the speedometer panel.
Thanks Kirkie.

[Volvorama]

I have been able to remove the knob for the dimmer in some cases. First move could be to remove the instrument and spay contact cleaner or even WD40 on the rheostat which is exposed on the rear of the speedo. Temporary solution might indeed be to attach (solder?) a wire bypassing the rheostat giving you dash lights on fully, this still being fairly dim in any case.
I presume that you have checked the bulbs and their holders.
If the temp and fuel gauge don't work it could be an earthing problem, usually due to the little brass nuts on the back of the instrument being loose.
Oh, and I wouldn't bother trying to access the rear but would instead remove the instrument. It isn't difficult.

[Kirkie]

Thank you Mark.
The temp and fuel gauges are working ok. Its just the dash lights.
Looking on a wiring diagram it shows the rheostat to be part of a PCB.
The lights behind the heater controls are also nil.
You say its very easy to remove the instrument. Could you please expand this.
Thanks Jim

[Volvorama]

Just had a look at one and the rheostat is removable by the looks of it. Problem I've had is pulling the little knob off but it can be done.
Complete instrument is held on by two white plastic fixings that you undo with your fingers. Don't forget to unscrew the speedo cable. Electrical connections are on big multi-pin plugs. Access is easier if you remove casing around steering column and also the fan switch. Instrument slides out forwards once you've laid it flat. Before starting it's a good idea to disconnect the battery in case you set it all on fire. The old Haynes manual does cover this, I believe. Remember first doing this on a '68 164 I had at University in 1981.
The option of by-passing the rheostat is still one to consider, as I tend to have the lights on maximum brightness anyway.

[Kirkie]

Thank you Mark.. Im going to do this when it stops raining.

Kirkie.

[Kirkie]

An Update..
My front seats are out .. gone to the upholsterers in Manchester for new
seat bases.
So a good time to tackle my dashboard lights.
I managed to remove the instrument cluster with a bit of fiddling and skinned knuckes.
The dimmer rheostat came away easily after removing the big screw and
the brass contact that slides along the coil fell out.
Anyway, I have bridged the two contacts and disgarded the switch.
Unfortunately, the dashboard lights still do not work. athough the light on the clock does.
I think I will have to employ a Auto-Electrician to explore the wiring with a meter.

[Derek UK]

I see no mention of the fuse box connections having been cleaned and the fuses freshened up/replaced as necessary. This is always a good idea. The dash lights might be on the same fuse as something else, maybe the interior light , so you have something else as a cross check.

[Kirkie]

The fuses were the first thing that I checked Derek. But thank you for reminding me.
All the other electrical accesories and interior lights are working ok.
The only thing that does not work is the seat belt warning.
I seem to be thinking that there is possibly a break in the pcb track on the back of the
instrument cluster as the lights at the rear of the heater controls are also U.S.
At 66 ..my digits do not work as good as they used to and im loathed to strip everything down myself. I do not do any driving in the dark these days , but its annoying knowing there is a fault even though she is 43 years old as she is a really good Volvo.
I am going to bite the the bullet on this one and get a professional to sort it out before my front seats go back in.

[Volvorama]

Now that you've got the instrument out you could take the whole thing to pieces and replace the circuit board with another one. These instruments come up on ebay every now and then too. Be careful though, there are two versions of the strip speedo, the later ones have a 'choke on' warning light and the circuit board is different.
I'm still surprised that the lights don't work as I've done dozens of these (since the '70s) and the failure has always been the bulbs or the dimmer. You're right about the heater control lamps as they also operate off the dimmer switch.

[Kirkie]

It seems a replacement circuit board is the next logical step.
I will look out for one.
Is there anyone in the community who can repair them if you send the unit to them ?
Thank you for the tip about the 2 variants.
Jim