KE70 - Fuel gauge drops when headlights are turned on.

[focus218]

Any solid advice before I start tearing up my dashboerd? Thank you.

https://imgur.com/a/hkMFY2a

[Banjo]

That is a strange one. Have you upgraded your headlights or the bulbs recently !

 There is no headlight relay in the early Corollas. The headlight current passes through the contacts in the headlight switch on the column. I can only suggest that when the headlights are switched on, the +12V to the dash assembly drops off somewhat. The fuel guage is fed by a regulated voltage less than 12V, so that the guage always reads correctly.  Are the headlights a bit dull also. I would measure the +12V at the steering column, with the headlights on & off, & see what the difference is. The regulator for the fuel guage can use a 7, 8, or even 10 volt regulator If the head lights are dropping the +12V supply to the dash, to less than 10 volts, that may be what is causing it.. My suggestion; is to have the headlight switch control an automotive relay only. Use the relay's contact to switch the +12V directly from the battery, via a 15A automotive fuse; to the headlights.

P.S. Have a read of recent thread, which may help you shed some light on the issue.

https://www.rollaclub.com/board/topic/85671-ke55-cluster-not-working-properly/#comment-738595

Cheers Banjo 

 

Edited Sunday at 09:59 PM by Banjo

[altezzaclub]

Fit this if you haven't already-

https://www.ebay.com.au/itm/177487513731?fits=Plat_Gen%3AKE55|Make%3AToyota&_skw=toyota+ke55+headlight+relays&itmmeta=01KWTATQAZEH18AW53VFYHEBS4&hash=item2953148883:g:wf4AAeSwLYlo7Qds&itmprp=enc%3AAQALAAABAGfYFPkwiKCW4ZNSs2u11xCm4UXQkL%2BH54Zn1Fi%2FK%2FCIxUre4eicbqIcF95OZ3t96q3XP9vLhknAsfBIOe48eDFmvIJRe3bpPw%2Fz1sSKPYDumWI8AZ5SB53LcKn3Yf0j12SROuHpLD%2FLX7ytBHgGOdGenbEhBoRSsLMw7UVJsyBhS7UKjgWoslCbmI95WhAvYTFyqP87W3JUdVfdD0vHf%2BQXMAeOpUMjDi6uPdRqoBDAow93TxGrZzWFtnfwEe15Nwcz1Mlse0h8qu154ciC%2F1NqyBVjz7DXeQJFCZl7%2BG4RjBRdClkDRxIt5oGKoj25zwzDMBYnGV5WSEdLWk1aIqQ%3D|tkp%3ABk9SR-b16srmZw

It takes all the heavy current out of the dash system.  Its well worth the $30, but you can make your own with a couple of relays, which I did in The Girls KE70 many years ago.

Then I'm afraid it will be tearing the dash out and cleaning earths and contacts and checking voltages...

[Banjo]

Hi Michalis,

                    The relay conversion, for switching the headlights on & off, will be one of the simplest, easiest modifications, You can do, for your Corolla !

Cheers Banjo

Edited Monday at 10:53 PM by Banjo

[focus218]

Thank you both.

I just ordered it and will try fitting it as soon as it arrives.