1988 GMC Itasca Sunflyer - 14.4 volt output not getting to the bus.

[sunflyer88]

Hello Fellow Motorhomers.   I Have an intermittent issue with the solid 14.4 volt output from the alternator - not getting to the main power bus - and not charging either chassis or coach batteries.   It will often start and only show over 12 V for a moment - then drops down to just the battery voltage. 12.0 v.    If one disconnects the batteries positive post - the engine dies. 

If I patch a gator clip from  straight off the alternator output stud (14.4 v) to the secondary starter solenoid positive - It will stay running - ie - voltage to the running ignition system and will charge both chassis and coach batteries.  (when connected)

I am really in need of a good schematic showing all the components.  Im pretty sure the large 8 gauge red wire - alternator output - goes from the alternator down to the starter /  common -  I would assume that large AWG starter cable then carries that voltage to the + buss somewhere ?   Any help would be very much appreciated - Thank you !!

[Mlw]

Type 1988 Chevy P30 chassis motorhome in your search engine and voila

https://www.irv2.com/attachments/photobucket/img_2144454_0_77d482e339751c8e648e5b4682af8fe2.jpg

It's the basics and as far as I know goes pretty much for all p30 Chassis Chevy's.

I found a lot by just following the wires and using a multimeter on search   -->+- if there's a buzzer in your multimeter it will beep when you find the right wire. I think a multimeter is something you really need if you want to fix your electrical issues

When you find the charging wire go to DC volts and see what you get. Normally the say when the voltage at the end of the wire is 10% less you need to replace the wire, but I think half a volt is allready to much.

If the wire is OK, you check for corroded connections, if that's also OK you go to then next point etc etc.

You can also become a member for a year and then find Chassis manuals, Wiring manuals, coach manuals and a lot of other things.

[sunflyer88]

Thank you Mlw - Excellent Schematic !!  Just what was needed,  It is indeed starting to look like the fusible link (large red from the alternator - and goes common at the main starter terminal,  I will do a continuity test - but now I know where the wires go.    I do have a multi meter alright - and I make use of alligator clips.. couldn't work without it.     I picked this motorhome up last year for a little over 3K,   Runs great - But needs a few things -  Next up will be the brake booster : .  But thanks again for the diagram ! 

[Mlw]

Somehow missed your answer, but you're welcome. Glad that I could help.

If you find your problem let us know what it was. 

[sunflyer88]

This was indeed the fusible link  8 AWG (wire) - From the alternator to the common power at the starter -  I got a length of 8 AWG wire an crimped it with eyelet connector (and a new rubber boot at the alt output stud)  and just  ran it to the battery isolator - always hot -  with an 100 amp fuse -  Now it shows good strong 14.5 volts runnning and charging main and aux batteries.   this is just common with the starter-  The odd thing was - The fusible link from the alt to the starter was showing 12.1 volts not running - but under load its like it would build up resistance and now allow charging -  The starter on these rigs is in a truly hideious position,  Under the exhaust manifold.  Which I just replaced the gasket -  I may replace it later - but I will just use and inline fuse - up  by the alternator - None of this nonsense having to remove the exhaust manifold to access the primary electrical  connections. 

Couldn't have done it with out you and your kindly provided schematic  !! Thanks again :  )   

BTW -  Do you happen to know where the 110v breaker or fuse panel in on these 1988 Sunflyers?

[Mlw]

Hey man,

Fantastic news, glad I could help.

I'm not familiar with the sunflyers but don't they have a powerstation? Normally the breaker is in this. Or else just look where your powercord is entering the RV and follow the line. by Removing draws and cabinetbottoms you can get behind cabinets.

Mine is in the kitchen area and looks like this. There is a panel in front of it to close it off.



By removing the bottom of the cabinet above (and the draw) i can get behind it and get to the wiring: