IVA Rear Fog Light Rules

[GarethGTR]

.....Hmmmn!

Is it me, or does that sound like they have written the rule 'around' existing car manufacturers?

Thanks for the post

[roy4matra]

PaulKemp said:

I would think a momentary switch and locking relay would do the job

Not quite since as Steve D pointed out it would not cancel the rear fog lamps when the head lamps are switched off. But the simplest solution is a momentary push switch, a latching relay, AND a normal relay. The normal relay is wired so that the input (30) is fed from the output of the latching relay, and its output (87) is fed to both the rear fog lamp AND the operation of the relay (85) with the other terminal (86) to earth. The dipped beam feed is connected to one side of the momentary switch and the output from that switch feeds both the latching relay and the normal relay terminal 85.

Now when you push the switch whilst the headlamps are on, the latching relay switches across to provide (dip beam) power to the second relay input. The momentary switch also switches this relay on, and the output then holds this relay on as well as provide power to the read fog lamp. If you wish to switch the rear fog lamp off, you push the momentary switch and the latching relay switches off. If the rear fog lamp is left on when you switch the head lamps off, the feed to the second relay is cut, so the relay switches off. When you next turn the head lamps on, the second relay is off, so there is no feed to the rear fog lamp.

Roy

[cerberatony]

I used a Cartek fog light switch, easy to wire and spot on for IVA

[CrutyRammers]

From http://www.locostbuilders.co.uk/forum/29/viewthrea...

VOSA said:

I am sorry for the reply that you received, it was incomplete and was issued in error, It appears that I sent without adding the reply text as the reference to the IVA manual is part of my base template, the actual reply was as follows,

We understand that there is some confusion over Note 4 in section 28 regarding the operation of rear fog lamps, the intention of Note 4 was to allow these options but not mandate them.

The requirement for the rear fog lamps are as follows:
The rear fog lamp(s) must only illuminate when dipped beam, main beam or front fog lamps are lit,

But the other conditions listed in the Note 4 will also be accepted if manufactured / wired up that way,

The manual is currently been amended and will clarify the operation of the rear fog lamps and the accepted alternatives, we have already issued a memo to all IVA Examiners with the correct information so VOSA Station should now be applying the correct standard.

Hopefully this will resolve your concern

For all the requirements regarding IVA can be found in the Inspection Manual which is free to download from www.gov.uk/vehicle-approval

many thanks

• *****

• *****

Approvals Policy Engineer
Approvals Scheme Management
Scheme Management and External Relations

[robcollingridge]

This is easily done with a cheap relay. Had not noticed this change for my next car but, will share circuit this weekend.

Rob

[CrutyRammers]

The point is, it's not needed!