C-95 Diesel Wiring Diagrams

[chuckbates]

I am having some electrical issues with my 1967 C-95 Diesel pumper. I apologize if the story gets lengthy, but I'm sure anybody with info to help will be asking for all the details anyway.

Prior to Memorial Day (Up to a month before) I had taken the truck out and about and ended up leaving the battery switch on. It may have been on for 2 days by the time a friend said he found it on. He switched it off and on my way home from work, I stopped and it fired right up. I figured no harm done, started and ran just fine.

Back to Memorial Day, a friend was going to take it to the local parade (I was taking my 1952 Dodge Power Wagon). He called and said it was dead. Battery chargers, tried jumping from Squad truck, jump packs,.... everything. Nothing helped. When I got there, I noticed the low air light wasn't even lit up with the chargers, etc. I knew something was wrong.

Being as busy as my group of friends are, we didn't get much time to do much with it for several weeks, like July timeframe. A couple of them took the batteries out and deep charged them. They put them back in the truck and it fired up. They drove it around and parked it closer to the fire station for servicing purposes. Came back the next day, stone dead. Batteries totally drained.

A week later, a heavy truck mechanic came and looked at it. Not much of a different outlook came of that, more head scratching was about all that did.

Into August we go - 3rd week of August we monkey around with charged batteries, a hammer to a solenoid and starter and it fired up. Ran it, moved it, put it on display for a local community event on a neighbors yard. Day after event - you guessed it (I hope) - Stone Dead.

I put chargers on. Tried jumping it with my diesel pickup. Both at once. Hammers. Pulled out hair....

Did some research on the solenoid the was mounted in engine compartment. Ordered a NEW 12-24 VOLT SERIES PARALLEL SWITCH FITS DOUBLE STAGE 1119845 (that is what was mounted in truck) The solenoid was toast. Cracked, Corroded. Full of dirt. Not sure how it was working to start with... So, when it arrived, I bolted it in and reconnected the wires (only a pair got mixed up and the one melted the insulation off in a hurry...) Once I rearranged the wires, the truck fired right up (batteries are holding a perfect charge as long as they are not connected to the truck). I was relived. That solenoid was $100....

So I took the old dog for a nice walk. Felt good to hear it, see it running down the highway. I was happy.

Until I stopped at my house. I shut it down to change the wire I melted the insulation off of. As soon as I was done with the wire, I was taking it back to the fire station lot and heading to my son's football game. Problem - truck wouldn't restart. Just clicking when you press the start button. I thought, well maybe the batteries aren't charging and while I ran it, the headlights were on, etc. So I put 2 battery chargers on it, got cleaned up and went to the game. When I came home from the game around 1030 (4 hours on charge), I tried to start it. Same clicking. For some reason, I decided to stick my head in the dogbox and look around. I starting feeling around and found that the block was stone cold, but the starter was warm, not hot enough to burn you, but warm enough not to keep your hand on it too long. Ah-ha, battery drain is coming from the constant voltage to the starter.......

Took the chargers off and said I'll deal with this Sunday (I had fire school on Saturday). When I woke up Saturday morning, I went out and just for shitz and giggles, I hit the start button and it fired right up. Interesting, once it all cooled off, it fired right up. So the voltage is always going to the starter, heating it up and draining the batteries.

So after the new solenoid was installed and the starter is heating up, I took off a couple wires from the solenoid to the starter and tried to start it. Fired right up. Great. Nope. Shut it off and it won't re-start at all. When the cables are hooked up, the "bendix" (I am not familiar with this at all, sorry) just spins not stop. It will not engage the starter. The truck just sits now, again.

The wires I took off are not original. Should the truck have 2 solenoids? Does anybody have any insight into this ordeal? does anybody have any wiring diagrams that might explain this? we are all stumped and really bummed out. The Dodge I have served with the Mack at the same FD, and I haven't been able to get them to a single parade together all year.

Again, sorry for the length, but it is the events that have led up to the C-95 just sitting.....

 

Thanks for any help in advance!

 

Chuck

[j hancock]

Here is a series switch diagram.  Hopefully it will help in diagnosing your situation.

https://www.bigmacktrucks.com/tutorials/article/70-wiring-schematic-for-series-parallel-switch/

 

[fxfymn]

You obviously have a very significant drain on the batteries if they go dead over night. Does this occur with the battery switch off? If so it has to be the wires that runs from the batteries to the switch since everything else is disconnected. The quick test is to disconnect the current carrying lead, most likely the negative cable since it should be positive ground, and observe the arc that occurs as you lift the cable from the terminal. An arc will only occur if there is current flow and the bigger the arc, the heavier the current flow.

The real test is to put an ammeter across the wire to detect current flow. With the battery switch off it should be zero. If there is flow I'd play with the switch first and then try disconnecting the wires from the switch to the load and see if that stops current flow. If so  it is in the truck's wiring and you will have to start isolating circuits to find out where it is. My bet is it is in the starting or charging circuits since the loss is so large and it is not kicking any circuit breakers.

For now I would disconnect the batteries altogether until you have time to trouble shoot it since it may be a dead short in the main wires from the batteries to the battery switch. If that is the case it could very well set the truck on fire while it is unattended.

[41chevy]

14 hours ago, fxfymn said:

You obviously have a very significant drain on the batteries if they go dead over night. Does this occur with the battery switch off? If so it has to be the wires that runs from the batteries to the switch since everything else is disconnected. The quick test is to disconnect the current carrying lead, most likely the negative cable since it should be positive ground, and observe the arc that occurs as you lift the cable from the terminal. An arc will only occur if there is current flow and the bigger the arc, the heavier the current flow.

The real test is to put an ammeter across the wire to detect current flow. With the battery switch off it should be zero. If there is flow I'd play with the switch first and then try disconnecting the wires from the switch to the load and see if that stops current flow. If so  it is in the truck's wiring and you will have to start isolating circuits to find out where it is. My bet is it is in the starting or charging circuits since the loss is so large and it is not kicking any circuit breakers.

For now I would disconnect the batteries altogether until you have time to trouble shoot it since it may be a dead short in the main wires from the batteries to the battery switch. If that is the case it could very well set the truck on fire while it is unattended.

Check all above BUT also check the Series Parallel unit very close like fxfymn says and I would look at the  ignition switch it self. Both will cause a  massive short in the start/ charge circuits

Let us know what you find.

Edited October 6, 2017 by 41chevy

[609albert]

I agree with my friend  FXFYMN  also check for any cable(s) that a chafing (rubbing ) on the body/frame.