Brake lamp fuse affecting gear change???

Mechanical questions about the Toyota Granvia
jarmmo
Posts: 52
Joined: 30 Apr 2011, 06:43

Brake lamp fuse affecting gear change???

Postby jarmmo » 26 Oct 2017, 19:53

Don't laugh, but my Granvia started to thud as I was slowing down to a halt at around 10 mph as it dropped into bottom gear, it only started doing this at the weekend after I changed a stop/tail lamp bulb. ( I said don't laugh !!). Yesterday i discovered that my brake lamps were not working, I checked the fuse, It had blown, the new fuse also blew straight away, I checked the bulb that I changed and found that one of the wire connections was skew wiff and was shorting the brake lamp out, after sorting this out and putting another fuse in the gearbox starting working perfectly again. I cannot explain this, maybe somebody else can shed some light on it. And no this is not an April fools joke in October.

Jarmmo

PUSHKIN
Posts: 25
Joined: 04 Sep 2017, 02:53

Re: Brake lamp fuse affecting gear change???

Postby PUSHKIN » 27 Oct 2017, 07:36

That is a baffler , i’ve texted a couple of techies I used to work with to see if they can suggest anything !?!?
Tony - 1999 3.4 V6 4wd Auto Camper located in Chorley Lancashire.

Richard
Posts: 446
Joined: 28 Oct 2008, 16:48
Location: S.E. London

Re: Brake lamp fuse affecting gear change???

Postby Richard » 27 Oct 2017, 11:30

Ah, so you've discovered a bit of Toyota's electronic wizardry to give smooth gearchanges!

My guess is that when you brake it sends a signal (using the feed to the brake lights) to the gearbox to say "get ready to change gear but not until the brakes come off"; when you release the brakes the gearbox changes down to the appropriate gear (if you're still travelling at high speed there'll be no change). With a blown fuse, the gearbox doesn't get the signal, so changes down (to a lower gear) whilst you're still braking. Normally, with a working brake light, you don't notice the gear change because it coincides with you releasing the brakes. To test this hypothesis, try rolling to a stop (using an upwards incline or the handbrake to get a similar retardation to using the brakes) without using the foot brake.

How convincing does that sound?

PUSHKIN
Posts: 25
Joined: 04 Sep 2017, 02:53

Re: Brake lamp fuse affecting gear change???

Postby PUSHKIN » 27 Oct 2017, 21:45

Ha ha, I have a Vanden Plas 1300 Auto with no electronic trickery and the gear changes when slowing down are nothing like the Granvia ! :-)
Tony - 1999 3.4 V6 4wd Auto Camper located in Chorley Lancashire.

jarmmo
Posts: 52
Joined: 30 Apr 2011, 06:43

Re: Brake lamp fuse affecting gear change???

Postby jarmmo » 28 Oct 2017, 10:39

Ha Ha, please don't tell me it is the Vanden Plas version of the Allegro. :lol:

PUSHKIN
Posts: 25
Joined: 04 Sep 2017, 02:53

Re: Brake lamp fuse affecting gear change???

Postby PUSHKIN » 29 Oct 2017, 02:01

No, the 1100/1300 version :-)
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Tony - 1999 3.4 V6 4wd Auto Camper located in Chorley Lancashire.

jarmmo
Posts: 52
Joined: 30 Apr 2011, 06:43

Re: Brake lamp fuse affecting gear change???

Postby jarmmo » 29 Oct 2017, 07:30

WOW! Very nice, I had the Austin 1300 as my first car MED 608F, very innovative in those days! Your is in better nick now than mine was then (1977)!!! :mrgreen:
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PUSHKIN
Posts: 25
Joined: 04 Sep 2017, 02:53

Re: Brake lamp fuse affecting gear change???

Postby PUSHKIN » 29 Oct 2017, 08:30

It’s not quite as nice as the pictures suggest (it is a 47 year old BL car after all) but it will be one day !! ;-)
Tony - 1999 3.4 V6 4wd Auto Camper located in Chorley Lancashire.

Richard
Posts: 446
Joined: 28 Oct 2008, 16:48
Location: S.E. London

Re: AP auto gearbox

Postby Richard » 29 Oct 2017, 09:50

PUSHKIN wrote:I have a Vanden Plas 1300 Auto with no electronic trickery

Wow! That takes me back! The Automotive Products (AP) 4-speed automatic gearbox was a remarkable design from the mid-sixties for several reasons:

- four ratios (plus reverse) was unusual for smaller cars when most automatic gearboxes had only three. I seem to recall that four were thought necessary because the small torque converter couldn't be designed to generate enough torque multiplication to mask the differences between the ratios. Plus each gear could be manually selected as well as just leaving it in 'drive'.

- it incorporated sets of bevel gears in an arrangement similar to a rear-axle differential, rather than sun-planetary gears which were tied-up in a range of US patents for use in automatic gearboxes.

- the whole gearbox package fitted even into a (slightly enlarged) Mini850 sump casing, with the torque convertor inside the clutch housing.

- and what I still find astonishing is that it worked using the hot and filthy engine oil for the hydraulic operation of the internal brake bands & clutches as well as filling the torque convertor, rather than the highly-crafted ATF which has to be kept pristine in today's modern designs. (Though I understand the oil filtration was uprated, I wonder what the service life was for those AP gearboxes.)

PUSHKIN
Posts: 25
Joined: 04 Sep 2017, 02:53

Re: Brake lamp fuse affecting gear change???

Postby PUSHKIN » 29 Oct 2017, 10:18

Yes it’s a fantastic bit of kit, i’m still surprised the gearbox gets the oil before the engine does, I think the gearbox gets it high pressure and the engine afterwards at a lower pressure !?
For all it’s faults the car always brings a smile to your face and in case any of you guys feel tempted the ADO16 club is amazing :-)
Tony - 1999 3.4 V6 4wd Auto Camper located in Chorley Lancashire.


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