70 Superior Rescuer Electrical Issue

James Fischer

PCS Member
Took the 70 Rescuer to PCS member John Arrington's shop (Emergency Vehicles Inc) last week to get a on-going electrical issue addressed and get a Federal siren mounted.

I would like to ask the experts here on the board if anyone has had any similar issues and what may be the problem.

Upon starting the ambulance all electricals work fine,however once the brake is applied everything cuts out EXCEPT the turn indicators.
All interior lights,brake lights,tail lights,emergency lights and motorola radio go
DEAD.
The strange thing is that it does not always do this.....but when it does it starts when the brakes are applied.

As John said all SUPERIORS seem to be wired just a bit differently and he WILL NOT re-wire the entire ambulance.:eek:

John is asking if anyone that may be familier with this type of problem to please contact him directly at 209-992-7236.

There is no use installing the siren until this issue is cleared up,so any and all ideas,suggestions or help would be very much appreciated.

Thanks to everyone in advance in getting the 70 back to her usual self !!
 
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my guess is that there is a broken wire that the something on the brake is bumping. it would be most likely the main wire going to the fuse panel. either the superior one or the caddy one. there is nothing harder to trace out then a interment open. the key is were do all those things get there power from? what one wire would cause all of them to go out. then start tugging . but the man has experience he is right on the superior wiring. strange and not one wire color coded.
 
I'm not an expert on ambulance-specific wiring, but I'll try to help. The first question I would have is if, when you step on the brake, all the lights are out until you change a fuse to restore them. Or, do the lights restore themselves automatically after a period of time, and you restart the car.

All things being equal, with a normal automobile, if you step on the brake pedal and it kills a bunch of accessories, I'd say that the brake light circuit goes directly to ground when the pedal is pressed. This would be considered a dead short. That's why fuses and circuit breakers were installed in the system, as a means of protecting against overheating wiring and possibly causing a fire. This same fuse or circuit breaker would also protect all your accessory lighting, along with the brake lights.

If you don't have to replace any fuses when you step on the pedal and the lights go out, I'd say that a circuit breaker is installed in the circuit so that when it cools off, it returns to a closed-circuit position. This would return the lights/accessories to normal. I'm doubting, although it's possible, that the mere addition of brake lights to the accessory circuit draws enough current to cause the circuit breaker to trip. But again, it could definitely be possible. An amp meter wired in series in this circuit (only this circuit, don't rely on the meter on the dash) would confirm or deny this. If it were me, I'd be hunting down a dead short somewhere in the brake light circuit, starting from the brake light switch which is most likely beneath the brake pedal.

If the amp meter confirms that the load exceeds the rating for the circuit breaker, I would then consider dividing the various loads among two circuit breakers, rather than just one.

Interestingly, I have a somewhat similar problem with my '60 Eureka hearse. The excess load of all the air conditioning components makes the feed wire through my key switch hot. I can feel it if I hold my hand near the key switch. As I currently have the dash board out of the car to repair a leaky heater core, I confirmed this visually when I noticed a brownish burned mark on the female terminal, where this thick wire feeds through the key switch. In this case I will have to install a relay into the circuit to help shed the load when the air conditioner is running. In other words, when I'm done the key switch will simply feed the coil of the relay (a much lower amp draw), and the rest of the load will be fed directly from the battery, through a fused heavy-gauge wire.

Good luck. I hope this helps.
 
70 Electrical Issue

Thank you Ed and Tom...:thumbsup::thumbsup:

The tips given will certainly be considered and hopefully through process of elimination the problem can be found and corrected.



Kent:
I have spoken to Calif Re-Wire for my Piner ambulance and they want waaaay to much money to re-wire....in reality I could probably find another complete ambulance for LESS money then the re-wire......and also they said that they "really" didnt want to tackle such a large project....that they could probably get 2-3 hot rods out in the same amount of time.

The tips given will certainly be considered and hopefully through process of elimination the problem can be found and corrected.
 
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standard GM would be if the brake light shorts out it blows the fuse for it. the dash lights will be on that circuit also. this is your indication that the brake lights are not working. I'm guessing from your statement that the headlights stay on. and what your loosing are everything that goes threw the master superior switch panel. they loved to use those in line fuse holders and every wire they touched was crimp spliced. the inline fuse holders in them selves are a problem as are the crimp connectors. with a superior you have to run each wire separately. so start with your hot wire from the switch panel. start at the panel and run it back to the source. look for the moving parts for the brake pedal moving that wire. tug all the crimp connectors and look for burnt fuse holders. there is no place on the car that the the warning lights are connected to the brake lights. if they were you would get them to flash if you stepped on the brake. thats not saying that some other owner did not try to wire them that way.

but do one circuit at a time the test light is your buddy here. superior added there wiring to the GM chassis. they did not mix them up with the exception of the rear door. most superiors were wired so that when the back ups came on the load light would come on. but when you opened the door they would only come on if the parklighs were lit . they robed the power for the door switches from the taillights.

the key to finding the problem is only take one circuit apart at a time. you get two or three things apart and you get mixed up in what goes were
 
Update

John and his crew were ablel to locate and fix the problem:thumbsup:.

Seems it was a bad solenoid.It is located underneath the car on passenger side behind the firewall.
A new CH solenoid was re-routed and installed in the engine compartment where a bit more protection from the elements/road is offered.:)

So now the installation of the Federal siren can start.:thumbsup:
 
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