Aha! A carver crusader is a cabin cruser I think you mean cascade same as I have and just rebuilt. First some advice DRAIN the system before winter on your last use or you will have same trouble I’ve had the tank parting from the housing when my tank argued with the housing. Our mechanic said its because it wasn’t drained before winter set in and frost gets at it.
Now for the heater . Three lights red green amber. Red shows when it fails to light the green showing its working amber showing the leisure battery current is too low so either battery needs recharging or replacing. If you replace get a 110v one.
Problem ; the gas module might need changing. The igniter might not be working, the gas might not be getting to the heater check for gas control valves (red gas taps.) the one feeding the heater may be in off position IF the last owner only use the built in emersion. Now for reset buttom this is on the back of the tank a white box usually fitted to the tank on the face of the box there is a slide sideways cover small this hides the reset button. The black box under the unit is the control system don’t mess with that. If none of this is of use contact a service engineer who wil carry out a safety test on all gas appliances and that they work statifactory. Ensure he covers why the Cascade water heater is not working.You get a pass certificate with this.
If yours is dual fuel then try it out on electric this will mean hooking up to mains and it should have a separate double pole switch and red light to say its on check the fuse if not. Now if it is not duel fuel and only gas its not a carver 2 its a carver 1.
Just for the record they are good but have been superceeded by Henry heaters much the same so no modifications required to fit one, if any.
hope this is of some help.
bob
June 2014