Community Forums

Seenamandah · 03-24-2025, 09:16 AM

Hello all,

So I'm very new and inexperienced with RVing and don't really have much experience with working on cars so please bare with me. I got a 1985 southwind fleetwood 7.4L P30 with a 454 motor. The RV was sitting for some years not sure how many and it didn't run. I asked previous owner why it didn't run and they didn't know. There was a previous rat infestation in the rv but the engine and wiring all look intact. I knew the batteries would be bad so I replaced the chassis battery but I'm holding off on getting the house batteries for now. I replaced the battery terminals and attached the new battery. Just to see what would happen, I turned the key and nothing. I did replace the fuses that were burned out in the fuse panel and also checked the fuses under the dashboard.
My question(s) is what should be my next step for diagnosing the problem?
Do I need the house batteries in order for the engine to start?

I'm just learning everything about RVs so please try to explain anything so it's easy to understand. Appreciate the help!

Flyer15015 · 03-24-2025, 09:41 AM

See,
A 454 Chevy is a good motor. Had one in our '87 Georgie Boy.
All it needs is air, fuel, and spark to run.
If, as you say, you're not mechanical, before you go tearing int to it, find a mobile mechanic.
You do not need house batteries to get her running.

Mike in Colorado

SafariBen · 03-24-2025, 10:36 AM

A helping hand is a good idea, it's easy to make more problems than you fix if you don't know what you're doing. Learning basic automotive electrical diagnostics is not that hard, lots of good youtube videos. I recommend a PowerprobeIII, but a $5 multimeter will do everything you need to diagnose most RV electrical issues.

To start with, did any lights come on in the dash? headlights? overhead light come on when you open the door? radio?

Seenamandah · 03-25-2025, 03:27 PM

Nothing at all

Paul_D · 03-26-2025, 11:16 AM

First question that pops into my mind - What burned out the fuses?
Sounds like a shorted wire/wires somewhere.

How many were blown?

Seenamandah · 03-26-2025, 11:20 AM

The glass fuses under the hood, some were burned on both sides. I replaced them all just in case.

FIRE UP · 03-26-2025, 12:07 PM

Seenamandah,
Well, this is your basic 12VDC investigation 101. This kind of stuff is fun for me. Especially since it's on a tad older coach with not all that much digital and high tech electronics. If you don't already have one, you need to get either a 12V test light or one of these:

https://www.amazon.com/Circuit-Autom...1zcF9hdGY&th=1

I have both a Power Probe and multiple 12V test lights and also a bunch of VOM's or Volt Ohm Meters. My Power Probe is about a $50 one and it works outstanding. You can pay a lot more but for us DIY types, the cheaper versions work outstanding. All are valuable in various stages of 12vdc testing and investigation. The test lights and even the Power probe are great for just testing for and locating the presence of 12V at various points. The Power Probe is also capable of displaying the amount of voltage at test points which is good because you might want to see if there's voltage loss along various stages or points of testing.

But, the starting point of course is the new battery. If you know how to use a test light, start at the battery just to make sure things work. Then, now begins the travel route of the 12v to see if it progresses to the next points. Yep, a pain in the a$$ for sure because sometimes places, components, relays etc. are hard to get at for testing of 12v presents. It always helps too to have a wiring diagram of your particular coach but, being yours is a bit on the older side, a wiring diagram most likely would be almost impossible to come by.

But basically, 12V starts at the battery and heads to a one or more of junction points or solenoids or relays or fuse boxes or all the above. But one thing I forgot to mention is, before you deep dive in to the world of 12V investigation, do yourself a favor and follow that battery negative lead from the neg batt post, to where ever it goes. In many cases on RV's, it will lead right down to the frame of the coach not all that far from the battery.

Those negative battery connections on the frame, live in about as harsh of an environment as possible so, corrosion or rust or both is potentially very high. When you find that neg batt connection, even if it looks in relatively good shape, take it apart anyways and do a thorough and clean cleanup of all that's involved with that connection. Your house battery negatives quite possibly will be in the same area. If so, clean those up while you're in the cleaning mood.

Now, with clean battery terminals, cables that you're sure are in great shape, and negative battery connections at the frame are now in tip top shape, NOW you can begin tracing down your issue(s). From this point on, it's now a process of elimination. That 12V starts at the battery positive and moves on to as stated, either fuse boxes or solenoids etc. This is where the Power probe is a better test tool. The 12V ground lead on just about all Power probes is around maybe 15' - 20' long and therefore, you can leave it connected to the battery negative post and still go quite a ways with the power probe to test various points.

And, in many cases, there's an extension to that ground lead that comes with those kits so, you can have a ground lead that's around 30' or longer which really comes in handy while you're testing at points quite aways away from a good ground. Those power probes have all kinds of features too. I won't go into all of them but suffice to say, you can also POWER something up with a power probe to see if a circuit still works but just doesn't for some reason, have 12V to it and now you're feeding it with 12V power. But, you have to be carefull when doing stuff like this because you can feed 12V where it's not supposed to go.

Anyway, again, this is sometimes a painstaking, time consuming process of elimination and it is what it is.

By the way, I too would be interested in just what "burned" up any of those fuses??? You say that the wiring in and or around the engine bay or compartment "seems" to be ok, correct? Well, it may be fine in that area but leading up to that engine bay from the batteries may be a total disaster from the little rat people causing havoc. Good luck and keep us posted.
Scott

Seenamandah · 03-27-2025, 02:09 PM

How do I know which positive lead goes to the main battery? The battery that was in it was disconnected along with all the house batteries ao I'm not sure which lead goes where.

SafariBen · 03-27-2025, 03:57 PM

Follow them to see where they go, one will go to the engine starter solenoid, that's the chassis positive, should be red somewhere on it. One of the others will go to the engine block, or the starter frame, or the biggest one going to the vehicle frame, that should be black.

Seenamandah · 03-28-2025, 07:35 PM

So the positive lead is hot all the way up to this blue box where the lead ends. I'm trying to find the ground end but I think it's on a solenoid. Where can I find the starter relay?

SafariBen · 03-28-2025, 09:18 PM

The ground should not connect to any solenoid or switch or fuse, it should be bolted directly to heavy metal. Follow the large cable from the starter solenoid back to the battery, that may have smaller cables leading off of it, those smaller cables may have fusible links in them that have blown, but that large cable from the starter solenoid will be the main positive battery cable.

The P30 chassis may be close enough to a van of the same year, to find what the start relay looks like and where it's located.

Seenamandah · 03-29-2025, 06:49 PM

This is what it looks like under the hood. Is the one with all the wires attached, the solenoid?

SafariBen · 03-29-2025, 08:46 PM

There is no THE solenoid, you probably have at least three solenoids, maybe a dozen or more. The third picture shows two solenoids or relays, kind of funny labeling, one should be house and one should be chassis, BUT that should not switch or control the battery to starter cable, it may control the ignition switch to starter solenoid signal so that the starter will not operate.

The blue finned thing with the large cables labeled chassis and house, I'd expect to have a large cable to the middle terminal, might be a sign of previous "repair efforts".