[Mgs] Dash Light Problem

daybell7 at aol.com daybell7 at aol.com
Tue Aug 28 05:27:24 MDT 2018

Thanks, Paul.  I’m checking dash ground first thing after much good advice, especially about not assuming it’s OK.   Both indicator lights work.  My tach was acting funny.  The car ran fine, but the tach never registered over 3k RPM.  Thanks for the good info, Paul and everybody else.

Steve H.  

Gainesville, FL

From: PaulHunt73
Sent: ‎Tuesday‎, ‎August‎ ‎28‎, ‎2018 ‎3‎:‎25‎ ‎AM
To: daybell7 at aol.com, mgs at autox.team.net

Usually the first step would be to bypass the dimmer rheostat, which may not be as easy on a padded dash as on the UK dash.  They usually have double spades for each connection, with two wires in a single spade on each connection, so it is a relatively simple test to move one of the connections across to the spare spade for the other connection.


Have you tested the bulbs work out of the sockets?


All the gauges should have earth wires on a 72, you can't assume the dash is earthed.  There should be a black wire under the fixing nuts that hold them in the dash, or could be a spade on the back of the tach case.  That is fed from a 4-way bullet connector that also feeds the right-hand indicator tell-tale, does that work?  The left-hand is fed differently.


Does the tach work as it should?  If so that would appear to have a good earth and it's bulb should work at least.  Are you looking at them in low light levels?  You won't see gauge illumination if the ambient conditions are bright.


Did you only have one bulb unscrewed when you tested for 12v in the socket and all the other bulbs screwed in and fitted?  You need to, especially if your test light has an LED or you use a voltmeter.


Take each socket out of the gauge and earth it with another wire.  Make sure your earth wire is good, can your test lamp check earths as well as 12v?




----- Original Message ----- 

From: daybell7--- via Mgs 

To: mgs at autox.team.net 

Sent: Monday, August 27, 2018 6:08 PM

Subject: [Mgs] Dash Light Problem

The dash lights don’t work on my 1972 MGB.  The trouble lite will light when I test the sockets, but various new bulbs won’t.  Does this mean low voltage?   I’ve grounded the test light on a bolt and assume the dash is grounded.


Steve Hughes

Gainesville, FL


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