Interesting electrical issue

[BPD109]

2002, Crown Victoria having some electrical issues in regard to radio and warning equipment.

Power is coming direct from the battery to a 70 amp, manual reset circuit breaker, by way of an 8 gauge wire. Runs into the car, and console to a fuse panel.

Power is split at the fuse panel to the siren, radio, camera, and accessories.

siren is a Code3 Vcon
Lightbar is a Whelen Edge, 8 strobe, 4 flasher
Radio is a VHF CDM1250

While in use, today, (stopped, emergency lights and radio on) everything went dead. No blown fuses, no tripped breaker, just everything went dead...then came back and cycled like that until the lights were shut off.

Rather than go to the police power relay, power is coming direct from the battery. Also, this car has had a quirk since put in service, the radio will shut itself off about 4 or 5 seconds after starting the car.

Suggestions? Install is very clean, and concise. Tracking wires is no problem,

[wx4cbh]

As a former tech/installer for the NCSHP, I can safely say that the problem you describe is not unique to CVs. A good, solid, COMMON gound point cures these symptoms 99.44% of the time. We put the ground point on a 1/4-20 bolt installed in the console as a stud(scraped the paint off and used star washers and a jam nut to secure) and tied it to a chassis ground with an 8 guage wire, usually the right A pillar grounding point beneath the passenger kick panel. The +12V side was wired like your CV. We NEVER used the Ford "noise source" harness provided in the police packages. Those harnesses seem to be death to those pieces of equipment with thin skins where noise is concerned.

I'd also recommend checking and confirming with test gear the grounding of the car body to the frame and to the battery. We've seen some problems in those areas before, too, and the symptoms were similar to the ones you described.

One trait the CVs seem to have after sitting for a long time with a high electrical load in warm to hot weather is that the alternator turn-on threshold seems to get higher under those conditions. We've had CVs just go dead while under those conditions and require a jump start. Others operating under these conditions jump back and forth from below 11 volts to 14+ volts as the alternator gets hot and starts the low speed cutout at engine speeds that should be above what's required. Sooner or later, depending on battery condition, those cars will eventually just quit, too. The heat and low RPM is a problem for the alternator and the battery and all the accessories just don't get the juice they need. Since a throttle switch like Diesel ambulances have isn't recommended for the gas engines, I don't have an answer except that the cars with poor grounds seemed to be the ones worst affected.

Also, there are some problems associated with the CDM series that are along the lines you describe. Sorry, but we had only a few of the CDMs and none gave us a problem, so I have no experience there. I'm sure someone'll be along shortly with good info on that subject.

[spectragod]

Grounds can be a #1 issue for failure, I have also seen cheap fuse blocks give up.

Ford has some serious issues with it's alternator going south as well, I have had some in the shop putting out 90 amps @ idle under load, but at 9.4 volts.

05' has brought some changes to the 03 - 05 cars different alternator, alternator pulley assembly with a clutch, upgraded wiring and a PCM upgrade that will bump the idle (when it see's a load) so the alternator will do 120+ amps @ idle.

The bottom line.... if all your components are quitting at once, you can rule out the component, ohm out your ground wires, and start to look for your loss of power, I would start at the fuse box inside the car just to verify +12V while it is under load, or ideally, after it has quit.
SG

[BPD109]

Grounding-All components share a common ground, 8 gauge to the chassis, bare metal and star washers. The CDM is grounded separately, but in the same manner using 12 gauge wire, I will check the battery terminals tomorrow, when the grounds are double checked.

I have been leaning toward a charging system problem and here's why. I took the CDM out of this car and put it in another CVPI, the problem with it could not be duplicated. I have seen a similar issue with older Spectras...if the radio wants more power than is availaible it would shut down. just wasn't sure if that could be an issue with CDM's.

Thanks for the suggestions and keep them coming.

[spectragod]

I would ohm out the ground wire, it may look good, but could still be bad.

Personally, I would lean towards the fuse box everything is hooked to, see way too many of those fail with a load on them.

SG

[nmfire10]

As far as the CDM is concerned, the ignition sense on them can be funny sometimes. If you cycle the power on-off-on or off-on-off, it doesn't always end up in the state you want it to be in. It would be very suceptible to the problems others have described here.

[apco25]

You really need to ohm out the ground..... you may have a connection, but if its crummy you will experience weird behavior like you have described.

Also i have noticed the Code 3 vcon boxes get very weird in bad ground or low volt situations. I've seen them catch fire as a result over over loading coupled with poor grounding.

[Rick Rock]

While in use, today, (stopped, emergency lights and radio on) everything went dead. No blown fuses, no tripped breaker, just everything went dead...then came back and cycled like that until the lights were shut off.

Is the lights running off the same circuit? If so, you may have too high an amperage draw with the lights on, or your alternator is getting weak. Try connecting the lightbar main feed to it's own power lead as see if it helps. Or just have the Alt. load tested.

[Dave]

The first thing I would have done is replaced (or bypass) the circuit breaker. Tripped or not it sounds like a breaker problem to me. Good luck

[Tech225]

Isn't 8G a little light for 70 amps? Also it sounds like a connection breaking down under load, either through heat buildup or just loose.

[apco25]

I have seen Code 3 v-cons do that, overheat and crap out after x amount of run time in a vehicle that had poor wiring (8ga) and grounds.

I tore everything out of this particular CV, replaced the main power with 4ga through a 100amp circuit breaker and replaced the ground leads at the battery and console.

The burning V-cons were in another vehicle including an ambulance chassis.

[EC-7]

8 gauge wire can handle 60amps @ 12-15volts.

I see that everyone says to check the ground with an ohm meter, this works most of the time. The preoblem is, most people test it with no load (everything off) and it can show a perfect 0 ohm reisistance. When its under a load, it will be strained and can be bad then. Ive seen some connections, both positive and grounds, show good at most loads, but at some certian points, they can go bad. It can be just that picky of a connection.

When ever I do mobile audio systems (2000+ watts, 100+ amps) I see EVERYONE use super heavy duty power cables, proper fuses and block, good chasis grounds, etc, but EVERYBODY forgets to upgrade the wiring under the hood.

You need a better power wire from the alternator to the battery, (as long as the alternator has the built in regulator) and also the battery to chasis, and alternator case or bolts to the chasis. 99% of the time, the stock battery to chasis ground is only good enough for the ~40-60 amps that your car needs for the regular electrical equipment. You need to upgrade the ground with as heavy of a wire you use as a main positive wire. You also need to either add on a larger alternator to battery positive wire or replace it with something that is heavy enough to handle everything. You also need to upgrade the alternator case to chasis or engine braided cables, cause those go bad too ( there most exposes to the elements and wear+tear).

When I have problems with funky electrical problems and large add-on's this almost always solves the problems, as long as nothing is defective.

[spectragod]

8 gauge wire can handle 60amps @ 12-15volts.

I see that everyone says to check the ground with an ohm meter, this works most of the time. The preoblem is, most people test it with no load (everything off) and it can show a perfect 0 ohm reisistance. When its under a load, it will be strained and can be bad then. Ive seen some connections, both positive and grounds, show good at most loads, but at some certian points, they can go bad. It can be just that picky of a connection.

When ever I do mobile audio systems (2000+ watts, 100+ amps) I see EVERYONE use super heavy duty power cables, proper fuses and block, good chasis grounds, etc, but EVERYBODY forgets to upgrade the wiring under the hood.

You need a better power wire from the alternator to the battery, (as long as the alternator has the built in regulator) and also the battery to chasis, and alternator case or bolts to the chasis. 99% of the time, the stock battery to chasis ground is only good enough for the ~40-60 amps that your car needs for the regular electrical equipment. You need to upgrade the ground with as heavy of a wire you use as a main positive wire. You also need to either add on a larger alternator to battery positive wire or replace it with something that is heavy enough to handle everything. You also need to upgrade the alternator case to chasis or engine braided cables, cause those go bad too ( there most exposes to the elements and wear+tear).

When I have problems with funky electrical problems and large add-on's this almost always solves the problems, as long as nothing is defective.

While I will agree that the problem could be an alternator, or bad wire at some point. I will disagree that the factory wiring would need upgraded with the current cofiguration(unless it has failed, which I doubt).

Thi car has no large add on's. This is a fleet police vehicle, not some POS duece & a quarter getting subs, amps and related accessories.

Since most of us offering up info make a living building fleet vehicles for a living, it is a good guess that we know the common prolems to look for in an instance such as this.

The original post said that he had run 8ga from the battery to a breaker and 8 ga into the vehicle, sounds like he remembered to upgrade under the hood. While 8 ga is a little light in my opinion, I don't believe that is the issue here. I suspect he has a thermal in the add on fuse box that most aftermarket company's sell, and/or a bad regulator in the alternator.

Since we have not heard back from the original poster, we do not know if this problem has been solved. But.... one thing is certain, in my 15 years of building police vehicles 5+ or so doing high end car audio, I have never seen the power wire from the alternator go bad or myself upgraded the power wire from the alternator.

With the exception of.......... When Ford replaces the alternator and upgrades the PCM on the 03-04 Vics with the 05 alternator, part of that little changeover is new alternator to battery wiring, but we are changing the alternator from a 140 amp unit to a 200 amp unit, so obviously, you would need to change it.

SG

[nmfire10]

8 gauge wire can handle 60amps @ 12-15volts.

That depends greatly on the length of the wire. 60 amps on 8 gauge is good for about 13 feet according to my handy chart. It's not a constant, the current you can draw goes down as the length of the wire goes up.

70 Amps with 8 guage is 11ft max which is more than enough to go from a battery to a console so he's probably ok.

[tvsjr]

Also keep in mind that the current-handling capacity is given as a function of temperature increase. Important variables are:
Size
Absolute resistence per unit length
Run length
Allowable temperature rise
Free-air or conduit run

Most tables I've seen specify allowable current over a given distance and assume free-air run of the wire. They also allow for a 20deg. Celsius increase in insulation temp.

If he's got his 8ga. wire-tied up in the middle of a wire bundle or in close proximity to the engine block, it's likely that such an increase would be a problem.

Personally, I'd run at least automotive-rated 4ga. for a 70A install. In my vehicles, I run 1/0ga., and will probably end up running two 1/0ga. runs in the new truck (one to drive the inverter @ 60A and the compressor @ 40A, the other to drive all the radios and computer). Fortunately, I have 260A of alternator to play with.

[jayres]

Hi all, I talked to BPD109 on the phone the other nite, I beleive he said it was a ground issue... Will holler at him to post his results... Jon

[BPD109]

Thanks for all the input, I have solved the problem. Turns out that the issues were two-fold. First, with the CDM, was a programming problem. It had been programmed for ignition sense.

Second, the electrical problem was ground related. Thanks to the marvel of Ford engineering, the negative battery terminal connector was not anywhere nearly as well affixed as it should be. I replaced both terminals with appropriate, and sturdy replacements, and I double/triple checked all other grounding points. Problem solved. the car was used at a DWI checkpoint a few nights ago (as an auxillary unit...) and it worked flawlessly for better than 3 hours, engine running, all equipment (minus siren) active. No failure.

As for the wire going into the car, took right about ten feet. For the power demands, 8 guage is ample for the current demand. In the next two months, the cars are getting a lighting upgrade of sorts, as we are going to Whelen Liberty LED bars. Gotta love that.

Thanks, again for the insight. It was much appreciated.

[apco25]

Bingo!

Grounds are IMPORTANT!

Simple fix and the car works properly. Good job.

[Jim202]

Just a note for what it is worth, instead of using an ohm meter to measure the wire runs and grounds, try doing a voltage drop measurement instaed. You won't damage your ohm meter and get a much faster clue as to where and what the problem is.

Take your meter and measure across the length of wire from the battery to the load. You may have to add an extension onto your meter probe, but it will show up poor conditions under the high current draw. The higher the voltage you measure, the worse the connections are. Do the same with the grounds. run the meter between the return of the device under test and the battery negative. If you see much voltage, start moving back in the grounding system until you locate the poor joint. This will be where you see the highest volyage.

Found a brand new CV had poor battery terminal connections right at the battery. Pulled the battery terminals off the battery, cleaned them and put them back on the battery posts. Never had a problem again with that police car. Just a bad connection right from the plant. Kind of surprised that it could even start the engine.

I tend to use some anti oxide compound on all the connections under the hood. It keeps the green stuff from forming on the connections.

Jim

Bingo!

Grounds are IMPORTANT!

Simple fix and the car works properly. Good job.