Hi, I wanted to thank all for your help. After following the post below, I crawled under the motor home checking the voltage to the starter solenoid and to the starter, everything checked out. I then told my wife to try and start the motor again. This time I tapped the starter solenoid and starter and the motor cranked. Subsequently, I have attempted several starts and all work according to Hoyle.
I have attached the post below in the order I checked things out in case it might be of use to someone else.
Again thank-you to all those who have tried to assist me.
Take care and God Bless
Barry, assuming itís an electric starter (some big trucks use air starters), there should be a solenoid. If youíre hearing a click when you hit the key, thatís the solenoid. Itís probably cylindrical, a couple of inches in diameter and a few inches tall. It will have a minimum of three wires attachedótwo large cables and one smaller wire. One of the large cables goes straight to the battery and should show battery voltage at all times (12.5v with engine off, 14v with engine running, 8v or more while cranking). The other large cable should have 0 volts unless the engine is cranking; it should show 8-10 v while cranking. Ideally, the voltage will stay above 10 while cranking; if it dips below 8, you may have dirty cable connections or a failing battery (how old is the battery?).
The third wire goes to the ignition switch and shows voltage only while the key is in the start position. If the safety switches (neutral or park, slides retracted, parking brake set, etc.) are not happy, there will be no voltage on this wire.
If the solenoid clicks when you hit the start switch, the circuit to the switch is okay.
The second big cable goes to the starter. When the small wire has 12v, the solenoid should click (once), and 12v should show up on the starter cable. If the solenoid clicks and you donít get 12v on the starter cable, the solenoid is bad.
If the solenoid chatters, it may be bad. Or, it may have a bad ground. They usually ground through the mounting bolts; remove the screws and clean the mounting surfaces down to shiny metal. Disconnect the battery cable first, and make sure nothing grounds out.
Make sure thereís NO voltage at the solenoid. Battery chargers, battery isolators, or battery booster switches on RVís can back feed from one battery to the other. None of these hot wires should ever be grounded.
If youíre getting good voltage on the starter cable...itís the starter. Or maybe a bad connection at the starter.
Sometimes if a starter is worn out, you can get one more start by rapping on the side of the starter with a hammer. This can cause the too short, worn-out brushes to shift enough to make the connection one more time. This may get you home or to a garage without a tow.