Motorhome engine and generator not starting nothing, no headlights either

[jeff york]

I suddenly have a no starting seeming dead battery situation. The engine, 454 and the generator have no starting power. The battery is fully charged. I also have no headlights or other exterior lights. As if the battery is disconnected. Here is what I noticed two days ago. I have a wire under the dash that has been tapped into. When I bumped against this wire, I could here something in the inverter panel click. As if a solenoid was clicking. I pulled the electrical tape off the wire and saw an ugly loose spice and the wire appears to come straight off the ignition. Last night I opened the inverter panel to inspect the panel and measure some voltages and check all fuses. What I believe is the red battery wire coming in has zero volts. What I believe is the coach battery red coming in has 12.8 VDC. I also checked all the fuses in the inverter and the fuses on the inside of the firewall. I do not know if there is a fuseable  link on or along the battery cable somewhere. My guess is that loose connection under the dash continued to make and break the connection after I let it go two days ag, This lead to maybe a fuse link or maybe the relay between the coach battery and engine battery burning up. Its a 1977 Airstream 454 P30 chassis. Any thoughts ? ideas. 

[david craft]

some older coaches ground engine to frame and then frame to battery. is the voltage drop across battery switch? just move a lead over and bypass switch..good luck

[Rich Thomas]

Jeff I had the simplest DC circuit throw be to the dogs because of a bad ground cable. it was on a gravely walk behind. it had new ends on it when I bought it off a neighbor so I overlooked it. while I was setting on the floor getting ready to replace about every thing but the cables I noticed a little pile of brown dust under the ground cable. What I found floored me. the cable had completely disintegrated into dust for about 2" inside the jacket. I felt like a real tool for not looking at it in the first place but hey the reason I own it today is the other guy got sick of working on it . I've had it for about five years now and it never fails to start. I this gets rid of your gremlins I think it would be wise for me to change mine as well.  

[Casey Chinook]

Hey Jeff,

Your quote:

"In the wiring diagram as I read it, everything past the starter is powered of off one 10 gauge positive line coming off of the starter positive post and going up to the main circuit fuse block on the firewall. With headlights and everything else, that seems like a lot for just a single 10 gauge wire. "

Based on the wiring diagram you are not getting voltage passed the starter to the terminal block to even turn on the headlights.That would indicate the problem is between the battery and starter. Replace the battery cables and you should be fine, If you still have no lights, something is up between the power entering the starter and leaving the starter to the main fuse block. I think you are getting close to isolating the problem.

[jeff york]

Thanks Casey, the blown fusible link may have been more like a fusible link that the end strands simply frayed to the point of no connection. but, then having my starter test bad and not even turn over when tested is puzzling. I am however going down your route and I am going to go buy new battery cable ends. You are correct. I could measure continuity and even voltage but once I turn the key and place a load on the circuit, a bad connection could cause the voltage to drop under load because the added load would add to the resistance of a bad connection at either the battery post or ground. Its a 77 so it has side battery posts and those stink anyway. So, I am going to convert it to a top post connection. 

In the wiring diagram as I read it, everything past the starter is powered of off one 10 gauge positive line coming off of the starter positive post and going up to the main circuit fuse block on the firewall. With headlights and everything else, that seems like a lot for just a single 10 gauge wire. For some peace of mind I am on my way to have new starter and old starter retested, buy new battery posts and go from there. 

[Casey Chinook]

Hey Jeff,

Sorry you are having such a tough time. Electrical shorts are the worst. I keep coming back to a bad ground cable or positive cable. I would try to get the headlights on first. don't worry about trying to start it. The cables can look fine, and only needs one strand to show continuity, but can still be bad because of corrosion and not carry the ground or voltage.  I think if you get the headlights working everything else will follow suit. I just don't get the blow fusible link and whether a no ground situation would cause it to blow. New battery cables are cheap...  Good Luck 

[jeff york]

This situation has become more complicated and confusing. I replaced the fusible link and it started instantly. I shut it off and a few minutes later it would not start. So, I pulled the starter and battery and took them in to have tested.  The battery came out with 840 amps. The starter was locked up. SO, they pulled out a new starter. It is more then twice as big as the one I pulled out. I always thought the starter I got previously was super small. 

So, I go back, install the new starter, reinstall the battery and secure all connections. I get nothing. NO start, no dash lights or headlights. Nothing. I place a meter on the lead to the starter. less then 12 volts and when I hit the key, its drops to zero. Even when I put the ignition switch in the ACC position the voltage on the lead to the starter drops to zero. I am measuring the lead at the dual battery switch. No blown fuses, and the fusible link is fine. I test the fusible link on the alternator and its fine. At this point I am grabbing at straws. 

My battery has side post connections. I hate side post connections. Since the battery has top posts too, I am thinking of replacing the side posts with top posts. I have studied the wiring diagrams in my original airstream manual. I am lost at this point. Did I say that already. I am an electrical engineer and can not figure out a simple DC circuit. But, its a bit of a modified cobbled up mess under the dash. I dont think its another fusible link or I would have a dead no power condition. I am thinking new battery posts and trying to eliminate the dual battery switch, possibly replace ignition but doubt I can get one locally for a 77 Chevy P30 based RV.

I am all ears for any thoughts. I think at this point I have confused myself and I am looking down the same pipe. 

[Rich Thomas]

Hi Jeff, sorry I'm in and out on this issue, I'm guardian for an elder uncle who has had major health issues the last few days and I have been away from my home with him. I am in total agreement on the load not short. I came home tonight and tried to get some pictures of the link hoping there was a part no. on it but nothing shows up. as you mentioned the insulation on the link is as big as that of the wire so that's not much help it looks like they crimped it on and used heat shrink tubing to seal out water. I will say that when it happened the tow truck driver thought my starter solenoid was stuck in because he said it was hotter than hell so he tapped on it with a hammer and thought he heard it snap back. I can't possibly agree with that because I drove 130 ish miles non stop before the fusible link let go. I would think that the electrics in this area should be pure Chevy P 30 but I guess that is debatable for the reasons you mentioned. very sorry I can't be of more help wish I was close by I would be more than willing to dive into it with you. 

[Erik Anderson]

Hey Jeff, Sounds like you need to search for the shorting Cause. I believe that this is the Ignition System Circuit. And that if it Melted The fusible link that you replaced, within a few minutes. It was doing it's job. Saving you from a possible Wiring Fire. You would benefit from researching  a wiring diagram, and trying to determine the direct Cause. As the link has done it's job twice now.

F.Y.I.

Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes (wire gauges), each fusible link is four wire gauge sizes smaller than the wire it is designed to protect. For example: to protect a 10 gauge wire, use a 14 gauge link (or for metric, to protect a 5mm wire, use a 2mm link). Links are marked on the insulation with wire-gauge size because the heavy insulation makes the link appear to be a heavier gauge than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Hope that this helps.

[Rich Thomas]

I have never really figured out why mine blew out it's ran through a metal  conduit to keep heat off it. I was tooling down the highway and lost everything. The only thing I can think of is I had turned the frig over to 12 volts for the journey home; 120 miles into a 150 mile trip it blew while climbing a big hill. The shop I took it to checked it out but couldn't find any problems and It's been fine since. Age,heat and too much current I haven't ran the frig on 12 volts since but I don't think it has a problem. That link is the only feed to the main fuse block up under the dash on my G 30. Probably the same on your P 30. glad you got it sorted out. only wish I could have gotten on a lot earlier and maybe saved you some time. 

[jeff york]

Ok, it was a fusible link on the starter. Odd that it knocks out the headlights and dash lights and pretty much everything else. I bought a 14 gauge Fusible link but it will not hold. So , I need to find out the correct size. Finding a fusible link locally does not seem easy. Now I have to find another one tomorrow and return back up to storage.