Speak to the stack tech help, they are really helpful.
Below is the manual for it plus the contact,
look at point 8 on the manual, I think the contact might be breaking when cranking so it is probably the 12v supply that needs to be changed.
http://www.stackltd.com/contact.html
http://www.stackltd.com/pdf/manuals_gauges/1292.pdf
Last edited by Caddyshack; May 22, 2016 at 12:38 PM.