1987 FC35 dead ignition circuit

[mattafact]

I was getting a low voltage alarm last night while boondocking. I used to aux battery switch to start the coach. After I turned it off i started checking battery voltages. My 4 6v bank was down to 8 volts. I pulled out my starting battery tray and there was a small spark but the batteries showed 13 volts. We ran a 14 gauge wire from the battery to the ignition terminal on that long strip above the batteries on the passenger side and it fired right up. Any ideas on what caused it?

[kg4rrx]

How do the cables look?

On that curbside tray, it can be easy to pinch the cable going from the battery to the starter, so watch that cable in particular when sliding the tray.

Also, the aux battery button really is only going to be good to get your generator going. The little generator battery won't last long trying to turn over the cat. Use it to get the generator going then charge the bus batteries if voltage is low.

[mattafact]

Originally Posted by kg4rrx

How do the cables look?

On that curbside tray, it can be easy to pinch the cable going from the battery to the starter, so watch that cable in particular when sliding the tray.

Also, the aux battery button really is only going to be good to get your generator going. The little generator battery won't last long trying to turn over the cat. Use it to get the generator going then charge the bus batteries if voltage is low.

Starting battery bank cables are new but they did fray on the frame and sparked when I pulled the battery tray out to check voltage.

[kg4rrx]

Originally Posted by mattafact

Starting battery bank cables are new but they did fray on the frame and sparked when I pulled the battery tray out to check voltage.

Frayed on the ends? Can you put up a picture of that?

[mattafact]

Originally Posted by kg4rrx

Frayed on the ends? Can you put up a picture of that?

No, just on one spot where it rubbed a piece of the frame. I don't think the starting batteries have much to do with the issue since it's the ignition switch that is dead without the lead directly to the battery.


The coach is at my inlaws. I'll be back there in a few weeks and will get some pics.

[Gene Mehr]

Make shure the A/C swith on the dash bibnt get turned off, just in case.

[Bill Pape]

Originally Posted by mattafact

I was getting a low voltage alarm last night while boondocking. I used to aux battery switch to start the coach. After I turned it off i started checking battery voltages. My 4 6v bank was down to 8 volts. I pulled out my starting battery tray and there was a small spark but the batteries showed 13 volts. We ran a 14 gauge wire from the battery to the ignition terminal on that long strip above the batteries on the passenger side and it fired right up. Any ideas on what caused it?

Most all 87,88,89 FC batteries were all tied together unless some one changed the wiring. Some batteries at 8 volts and others at 13 volts is confusing. Recheck this wiring, I am also confused about the terminal strip on the passenger side, Can you show a picture?? Sparks are not good

[mattafact]

Originally Posted by Bill Pape

Most all 87,88,89 FC batteries were all tied together unless some one changed the wiring. Some batteries at 8 volts and others at 13 volts is confusing. Recheck this wiring, I am also confused about the terminal strip on the passenger side, Can you show a picture?? Sparks are not good

Hi Bill,


Sorry for the confusion. I wrote it on my phone in the desert while diagnosing and rushed it.



My starting batteries were added earlier this year and are isolated from the house bank with an isolator. They were at 13 volts. The 4 house batteries on the driver's side were the ones down to 8v. That terminal trip was above those on the driver's side.


I will get pics when I get back over to my inlaws' house.

[kg4rrx]

How long had you been parked? And how old are the house batteries?

[Bill Pape]

Originally Posted by mattafact

Hi Bill,


Sorry for the confusion. I wrote it on my phone in the desert while diagnosing and rushed it.



My starting batteries were added earlier this year and are isolated from the house bank with an isolator. They were at 13 volts. The 4 house batteries on the driver's side were the ones down to 8v. That terminal trip was above those on the driver's side.


I will get pics when I get back over to my inlaws' house.

Thanks , I got it now, if you added a good 12 volts to that ignition terminal above the batteries on the driver side, This by passes the ignition wiring under the dash, I would be checking the ignition key switch, and the wiring under the dash from the key switch to the cannon plug, the pins inside the plug over heat and do not make a good connection. I would suggest looking at the plug and jumping over the plug with wire to eliminate this trouble intermittent situation. I am not at my bus with this fix information, but IIRC, there are atleast three wires in the middle of the plug,, maybe numbers 10, 11, 12. if these wires are not repaired I would do so anyway,
sooner or later this plug will make you unhappy, maybe at a fuel station stop or an intersection