I need the help of the Barth Wizards, especially those that have been through the hunting down of electrical problems. I have an '84 25' Regal on top of an '82 P30 chassis powered by an '82 Chevy 6.2L Diesel. I have no electrical power, at least nothing at the ignition switch. The interior lights do not even come on when the door is opened. Battery is fully charged. On the P30's, is there a connection block or some area of electrical connections that are noted for corrosion? Is there a fuse or fusible link in the system for which I should look? Any and all ideas are appreciated. With the Rally in three weeks, I really need to get the issue resolved.

Thanks.

How many batteries do you have? You mention "battery" in the singular. Your reference to ignition switch and interior lights would indicate that both coach and chassis batteries are dead, if you have amulti battery coach. Do you have a hot light?

I have a single 12 v battery (for a diesel) for the chassis and went with the 12v pair of deep cells for the coach. (We rarely head way off the beaten path) The light I am referencing is actually two lights. One is under the dash at the driver�s feet and one just as you open the door in the first step. I have assumed that these two lights function similar to the interior lights of a car, i.e. these come on when door is open and run only on the chassis system. The two deep cells seem to be charged, at least that is what the indicator for the generator/ coach batteries on the dash indicates when the generator is on. Since nothing is happening with either the ignition (Chassis side) key or the auxiliary start (coach batteries), I am going to look at the isolator connections first. Perhaps these are corroded. How does one tell if the isolator is bad? Why would one go bad?

In the past, I have noticed two �fuses� near the isolator. Are these anything special or the standard 20 and 40 amp, 12 volt fuses that you can find hanging on the rack at places like AutoZone? Perhaps one of these is my problem?

Anyway, I have my volt meter and my Barth & GM wire diagrams in hand and I am off to start the adventure. If you have any further thoughts, please pass them along.

I have an 84 gasser, so some is similar. The isolator is only involved with charging. you can check it out with your voltmeter. The voltage at each battery or pair should rise to 13.5 or 14 when the engine is running. If it does, your isolator is partly good. If you also read zero voltage on the large terminal of the alternator when the engine is off, the isolator is wholly good.

So if I am correct in assuming that your problem is in the chassis battery, let's go there. You should have a good clean and tight connection at the at both battery posts and at the big terminal on the starter. Take the nut off and clean everything shiny and put it back together. Even if that is not the problem, it is good to do this periodically. Do you have 12 volts from there to ground? Basically, just physically follow the positive wire and check for 12 volts wherever you can. And be sure you have a very tight clean ground connection from battery to frame and to engine block.

You say "nothing at the ignition switch----have you verified this with a meter or light?

For trouble tracing I like to use a test probe light. You can poke through insulation to read at the conductor. It looks like an icepick with a bulb inside. Saves lots of time.

Thanks for the confirmation on a logical way to approach the problem. I cleaned the isolator connections first. Actually, every electrical connection that I could clean, while working on this problem was cleaned. You�re right, if you�re there working on an electrical problem, go ahead and stop a future problem from occurring by cleaning the connection, especially with so many connections exposed to the elements.

The battery terminals were cleaned when I reinstalled the chassis battery. The chassis was still without power. As you suggested, I started with the next major ground wire. That was the problem. It was loose at the starter. It had arc�d a few times, so removing the nut was a little challenging. In order to insure a good connection, I opted to put on a new nut when reassembling it. This took care of the no start off the chassis battery.

The �no start� issue using the auxiliary starter was found to be a broken wire on the auxiliary starter relay (which is just a standard Ford, fire wall mount, starter relay, about 6 bucks). So, both problems have been solved.

Now, I�m trying to figure out how to change the belts. I�ll start a new post on that topic.