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Need to replace the bulb in the stop light in the boot lid (1990 NA6).

Bulb removed is mostly unreadable (says Austa 12Vsomething - think it is 12V11W but can't really tell).

My Service manual electrical diagram implies it is a 18.4W bulb (lists the 2 brake lights as 21W).

Anybody able to shed some light (pardon the pun!) on exactly which bulb I should be looking for to replace?

Wattage would be good - bulb number etc. would be even better.

It is a wedge type bulb (i.e. not a bayonet type) if that info helps.

Any and all help is appreciated.

OK - an update.

I searched everywhere - big forum and google and came up with multiple answers.

MX5Parts.uk sell a 21W bayonet type - wrong one.

US versions seem to differ between a bayonet type and a wedge type.

The only mentions of wedge type wattage I could find in reference to the bootlid stop light was 18.4W.

Went to local Taxi servo (figured if they saw lots of taxis they were likely to stock various bulbs as most servos have nothing - logic proved correct).

Went through their stock - no 11W wedges but they had 18W wedges so grabbed one (Austa 12V18W).

Inserted into bootlid stop light and all good (figured if no good that I would blow a fuse).

Info for anyone else who may need this.

Would be nice if I could get a reliable list of the bulbs (types/wattages etc.) but doesn't seem to exist from what I can see.

rpost77 wrote:Need to replace the bulb in the stop light in the boot lid (1990 NA6).

Bulb removed is mostly unreadable (says Austa 12Vsomething - think it is 12V11W but can't really tell).

My Service manual electrical diagram implies it is a 18.4W bulb (lists the 2 brake lights as 21W).

Anybody able to shed some light (pardon the pun!) on exactly which bulb I should be looking for to replace?

Wattage would be good - bulb number etc. would be even better.

It is a wedge type bulb (i.e. not a bayonet type) if that info helps.

Any and all help is appreciated.

I recently changed mine. It uses a 21W bulb. Since it is a brake light like the other two brake lights it needs to shine with the same brightness. 18W would not be legal.

The bulb is readily available- Bursons will have them. These are common fitment to older high mount stop lamps. I would say it is a W21W with a W3x16D base - that bulb is 39 x 20mm. There is also a W16W this is known as 12 21cp a US type and it is 35X15. The first one should be the right one. Take the sample or just check the dimensions. Incidentally Austa is a "cheap" brand of bulb in many servo's and on old memory tells me ( maybe incorrect) that it came from a bloke called Austin Halliday who worked for one of the lighting co's- treat this as hearsay.

You should be able to get bulb listings and info from lighting co's eg Philips, Osram or from web sites Narva Hella etc. Bursons etc may have some charts- they certainly display them in store.

re-thinking 921 sticks on my mind as a type and the 2 bulbs I mentioned have different bases so it is probably 12/21CP ( 16W). At the time the first bulb was selected it was not an ADR ECE type. The sample will tell you immediately by its dims.

Japanese vehicles did not follow the same rules as Aust and it was common for them to specify bulbs measured in CP eg stop and tail which 12v 32CP and 12V 32/4CP which were replaced by 21W and 21/5W.

Mate, Supercrap Auto has a book that you look up your model in and it lists every bulb. Just take your old bulb in to make sure it looks the same, because I have spotted one error in the book before.

I just replaced one in my '94 NA8. The Mazda part number for the high mount stoplight is 921. According to my owners manual the required bulb is 18.4w, whereas the the combined stop/taillight is 21/5w.

J

921 is the type number its not a Mazda nbr

Go to Jaycar and purchase an LED replacement and enjoy the fact that it will illuminate 0.4 secs quicker than an incandescent lamp, providing following vehicles with about 11 metres extra warning at 100 KPH, will not generate heat and therefore reduce condensation and last far longer than the original bulb.
Greg.

And they come in RED!

So Jaycar has a replacement LED single bulb with the same base- or is a replacement a complete lamp with the same dimensions as the MX5 unit?. Very easy to just replace a bulb I reckon.

Sure led's are faster but just how much difference in makes in the real world is debatable esp considering the vast majority of vehicles are still using good cost effective incandescent light sources. If you do not see the light a driver is probably too close or not watching.

Heat is not remotely an issue. All incandescent car lights are built for purpose - even tail lights burning for long hours continuously or headlamps are not adversely effected by heat provided some cowboy hasn't managed to replace the light source with an unapproved or non standard bulb - eg excessive wattage. Insofar as a stop light used intermittently is concerned drivers can be assured that the lamp will not melt.

Condensation in lamps is normally caused by a failure of construction - eg welding continuity or venting etc.

Mr Morlock wrote:All incandescent car lights are built for purpose - even tail lights burning for long hours continuously or headlamps are not adversely effected by heat provided some cowboy hasn't managed to replace the light source with an unapproved or non standard bulb - eg excessive wattage.

Do you reckon every NA with melted Parking Light internals (the bulb holder) has had incorrect bulbs installed? I'm yet to meet an NA owner who doesn't have this problem. I'm trying to work out whether it's worth replacing the entire unit at some point, because if it's a design fault then it's not worth it.

Mr Morlock wrote:So Jaycar has a replacement LED single bulb with the same base- or is a replacement a complete lamp with the same dimensions as the MX5 unit?. Very easy to just replace a bulb I reckon.

Sure led's are faster but just how much difference in makes in the real world is debatable esp considering the vast majority of vehicles are still using good cost effective incandescent light sources. If you do not see the light a driver is probably too close or not watching.

Heat is not remotely an issue. All incandescent car lights are built for purpose - even tail lights burning for long hours continuously or headlamps are not adversely effected by heat provided some cowboy hasn't managed to replace the light source with an unapproved or non standard bulb - eg excessive wattage. Insofar as a stop light used intermittently is concerned drivers can be assured that the lamp will not melt.
Condensation in lamps is normally caused by a failure of construction - eg welding continuity or venting etc.

This reads so much like a two- way bet from a bloke with too much time on his hands, and yes Jaycar do have bulb only replacements.
Greg.