Help out some firefighters with an ambo problem!

[ADDirishboy]

Here's the deal. We got a 2002 ambo with a 7.3L Powerstroke motor. We have a power drain somewhere, and we cannot find it. Anyone have any experience with these motors that are having the same problems? We're getting sick of hooking it up to a charger every time we run a call. Any help would be greatly appreciated.

[Encryptshun]

I'm going to try to translate that into English. Please tell me if I'm wrong.

"We have a 2002 ambulance. It has a 7.3 liter Powerstroke engine. The alternator cannot keep the battery charged when it's being all ambulanc-y. What's wrong?"

If that's your question, I'm gonna go with "you have a bad alternator".

If that's not your question, I can't help you.

By the way, why do you wear red suspenders?

[ADDirishboy]

No, it's not the alternator or anything having to do with the alternator. We've checked multiple times and replaced it just for s*** and giggles.

As for the red suspenders, I wear black. They look cooler.

[frapjap]

Is the alternator charging the battery?

Maybe someone grounded something out when changing the last alternator because they didn't disconnect the battery and blew a fusible link?

Everyone knows glow in the dark suspenders look the coolest.

[ADDirishboy]

Yes, the alternator is charging. All fuses have been checked. Captain just told me there is a 26 amp draw on the battery. Not sure how he just found that out though.

[Encryptshun]

True I'm an electrical tard, but a 26-amp draw and no fuses are blowing? So I'd say that rules out anything in a circuit covered by a 25, 20, 15, 10, or 5 amp fuse.

What circuits does that leave?

[ADDirishboy]

The hell if I know. I don't do electrics. I'm sure that thing has some massive fuse on it somewhere though. I'll check for any we may have missed.

[IanS]

That is a HUGE draw. Like HUGE.

Start tacing. The energy is going somewhere. Hook an Ammeter up between the battery and the positive cable. Start removing fuses until the draw disapears. When you figure out which fuse it is, move down that circuit. Unplug suspect accessories until you find the culprit.


The only time I have ever seen a draw that large is when an Alternator shorted internally. Very few circuits on a typical vehicle can sustain that kind of current flow. Most notably the charging system, and the starting system. If you have already changed the Alt, then I would look to the starter.

[Chaotic_Warlord]

Are you running a dual battery 24V system, if so check your secondary alternator. What's the amperage for the air compressor, mobile EKG, and the lights and sirens. Do you have the same problem when you aren't on a call? If not then it has to be be drawing from one of the multiple pieces of equipment. None of the other firehouses have had this problem? What model Ford is it, some of the newer trucks are using the F450 and F550 chassis and those are the only ones still using the 7.3 ( the 6.0 phased out the 7.3 for MY 2002) Just like any car related question asked on here, you need to provide the same amount of info for this.

FlatBlack, 26 amps on a vehicle like this isn't out of the question, especially if it's a 24V system. Remember, this is a specialized service vehicle, it needs to power practically everything you would find in an ER, EKG's, defibrilators, oxygen pumps, a ton of computerized monitoring equipment and life support systems. Plus I do believe thet have aux. docking stations to plug in 110V and 120v power cords.

[IanS]

FlatBlack, 26 amps on a vehicle like this isn't out of the question, especially if it's a 24V system. Remember, this is a specialized service vehicle, it needs to power practically everything you would find in an ER, EKG's, defibrilators, oxygen pumps, a ton of computerized monitoring equipment and life support systems. Plus I do believe thet have aux. docking stations to plug in 110V and 120v power cords.

I am by no means saying 26 amps is out of the question. I have seen it before on light trucks. 12 or 24 volt, a key off draw of 26 amps is MASSIVE. A typical vehicle will have battery drain issues from anything more than a single amp draw.

Collectively all of the accessories may pull massive amounts of juice, but with the vehicle off, they should also be off, and drawing next to nothing. Which means there is likely 1 single thing that has failed.

Heavy duty vehicle or not, they still run many circuits independently (unless the customizer was retarded) to isolate different units circuits so if you pop a fuse you dont lose everything. These individual circuits are, for the most part, not capable of running that sort of draw for any length of time without burning out the wiring/fuse.

This leads me back to starting system, charging system, or possibly a auxiliary AC unit.

If the draw truly is 26 amps, then you can rule out any circuits fused for less then 25 amps.

[Encryptshun]

Maybe your dirty hippy neighbor is siphoning power to augment his photovoltaic solar array. Next time you find the battery dead, see if you can smell patchouli.

[4cefed]

Finding power drains is even less fun than opening the ark of the covenant and looking at the contents.

Do like Ian suggested. Are they truly 24V systems or do they just have 2 12V batteries? There is probably a distribution block somewhere for all that equipment. If you can't find the drain by pulling all the fuses, you may have to unhook cables connected to the positive terminal(s?). I would bet there are multiple fuse panels or distribution blocks throughout the vehicle.

If you discover what fuse/leg it's on, see what equipment won't work anymore and start playing with that stuff. Chrysler liked using these "fusible links" on stuff back in the day. They look like normal wires, but they contain a piece that will melt on an overcurrent and break the wire. I don't know if they are used anymore or if Ford used them, but that would be something that would have to be unbolted or physically disconnected somehow.

For a quick fix while you are finding the culprit, you could install a master battery disconnect, they make a nice rotary knob connected to the positive terminal. It would reset the vehicle's ECM every time, that may not be healthy, but having a dead ambulance when someone's life is on the line could be worse. Hope you get it solved.

The glow plugs aren't stuck on are they?

[Chaotic_Warlord]

Finding power drains is even less fun than opening the ark of the covenant and looking at the contents.

Do like Ian suggested. Are they truly 24V systems or do they just have 2 12V batteries? There is probably a distribution block somewhere for all that equipment. If you can't find the drain by pulling all the fuses, you may have to unhook cables connected to the positive terminal(s?). I would bet there are multiple fuse panels or distribution blocks throughout the vehicle.

If you discover what fuse/leg it's on, see what equipment won't work anymore and start playing with that stuff. Chrysler liked using these "fusible links" on stuff back in the day. They look like normal wires, but they contain a piece that will melt on an overcurrent and break the wire. I don't know if they are used anymore or if Ford used them, but that would be something that would have to be unbolted or physically disconnected somehow.

For a quick fix while you are finding the culprit, you could install a master battery disconnect, they make a nice rotary knob connected to the positive terminal. It would reset the vehicle's ECM every time, that may not be healthy, but having a dead ambulance when someone's life is on the line could be worse. Hope you get it solved.

The glow plugs aren't stuck on are they?

Nice mention of the glow plugs, but I would think that if that were the case they would burn up or burn out and then they'd have a much larger issue at hand.

Depending on which company built this ambulance (it sure as hell wasn't built by Ford) the circuits and wiring diagrams will be different from builder to builder.

Also Are you sure your CO said their was a 26 AMP draw, or a 26 Volt draw? There is a HUUUGE difference, 26 volts tickles, 26 amps is fatal. Just sayin'. When you replaced the alternator did you go to Autozone and pick up one off the shelf or did you actually order one specific for ambulances? If you just threw in one meant for a diesel E350 that Bob the plumber uses it's not going to be strong enough to fully charge the battery, so every time you go on a call and actually put some strain on the battery it's going to pull what little life is left in the battery to require a a jump next time you get a call. In the event that you are actually using the correct alternator verify that it is wired correctly, if the polarity is reversed then you're definitely going to have a power draw.

[IanS]

Depending on which company built this ambulance (it sure as hell wasn't built by Ford) the circuits and wiring diagrams will be different from builder to builder.

Also Are you sure your CO said their was a 26 AMP draw, or a 26 Volt draw? There is a HUUUGE difference, 26 volts tickles, 26 amps is fatal. Just sayin'. When you replaced the alternator did you go to Autozone and pick up one off the shelf or did you actually order one specific for ambulances? If you just threw in one meant for a diesel E350 that Bob the plumber uses it's not going to be strong enough to fully charge the battery, so every time you go on a call and actually put some strain on the battery it's going to pull what little life is left in the battery to require a a jump next time you get a call. In the event that you are actually using the correct alternator verify that it is wired correctly, if the polarity is reversed then you're definitely going to have a power draw.

A "Draw" cannot be measured in volts. Only in Amps.

Unless of course someone just hooked a voltmeter up to the battery of a running vehicle with a 24 volt system. In that case it would likely read around 26 volts. Hmmmm.

Come to think of it, a 26 amp draw would blow the fuse on anything other then a class 2 DVOM. Which most are not.

[ADDirishboy]

Alright, so we took it to our specialized mechanic and had him look at it since it was just pissing us off.

Ian, you were dead on man. MAJOR issues with the starting system. Don't know exactly what, but all I know is it wasn't cheap to fix. They had to do some pretty intensive s*** with the wiring throughout the ambo and replace a ton of crap.

FlatBlack, 26 amps on a vehicle like this isn't out of the question, especially if it's a 24V system. Remember, this is a specialized service vehicle, it needs to power practically everything you would find in an ER, EKG's, defibrilators, oxygen pumps, a ton of computerized monitoring equipment and life support systems. Plus I do believe thet have aux. docking stations to plug in 110V and 120v power cords.

Not sure what cities you are referring too, but the VAST majority of ambo's that I've been in have nothing like that on them. Yes, lights and sirens take up a lot of power, same with the flourescent lights, huge A/C system, radio's, GPS, etc. But our EKG is a portable monitor that's powered by 24v Dewalt batteries, defib unit built into that monitor. Besides, defib doesn't take very much energy to use. O2 pumps, nope. Just an o2 bottle that is turned on manually and has a regulator on it, nothing electronic there. And I really don't know what other life support system's would even be on an ambo. We can't do a whole lot in the field. Mainly hook them up to the monitor, check vitals, throw them on high flow o2, start an IV, push some drugs, and haul a** to the ED. Honestly, not a whole lot else we can do.

[IanS]

hurray for the amber lamps.

[Dattebayo]

the VAST majority of ambo's that I've been in have nothing like that on them.

Just curious, but how many have you been in? It sounds like thousands from the way you make it sound...

[ADDirishboy]

Just curious, but how many have you been in? It sounds like thousands from the way you make it sound...

Phoenix- about 4
Rural Metro- 3
Tucson- 5
PMT- 2
Southwest- 3
Sunsites- 3

So about 20 all together. Not a ton, but if you think we're stocked like a f*** ED or OR, you're way wrong. Most everything we have that is electronic runs off of batteries, not the truck itself, since we have to be able to take most everything into someone's house.

[Dattebayo]

Right, and I guess that makes sense, but DeWalt batteries? LOL!

[ADDirishboy]

Yup. Not every city uses DeWalt, obviously, but they are the same style as the cordless drill unit's.

[Chaotic_Warlord]

Here in Philly the PFD have massive ambulances that use the Ford F650 chassis and have to be ready for any emergency. I'm sure the smaller E350's can't supportthe load out that I mentioned, but the EMT's here and a lot of the major cities along the NE have to have what is needed to go to any call due tothe events of 9/11. Also a bus has to report to every fire call and the PFD is who comes out to every death before the Coroner or funeral home can take the body. Just out of curiosity is AZ one of the states that a Paramedic has to roll with the bus or do you guys roll to calls solo? A Paramedic has to roll out with the EMT's in NJ bc the EMT's don't have the same medical training, the can do most of the Paramedic job, but can't do major life saving stuff like in field surgery or emergency trachiotomys.

Just saying, just bc you havent seen the equipmentb I mentioned on your busses over there doesnt mean that that is the case everywhere, we dont exactly have the luxory of air evacs here in the city, and when they do go out its for a traffic accident on I95, otherwise if your shot or your run over by a semi truck in city itself you better pray that the ambulance coming to save you has all the equipment and the EMT's are trained to do everything they do in the OR because your a solid 15-30 minutes fom the nearest ER.

[ADDirishboy]

We have BLS only unit's, but not many. Most are ALS with a medic and an EMT. Also, your medic's can't do trach's? WTF?

I'm also having a hard time understanding why your guys would need anything like an o2 pump. Are you just talking about something like an automatic BVM?