Ive put a set of strobe lights on my limo I take to shows. Im pretty familiar with all kinds of electronic dodads in cars. Ive rewired cars and limos from end to end. Heres one that has me stumped.. Looking for ideas from anyone whos had or installed them. Both of them flash like theyre supposed to behind the grill. After about 10 mins, they shut off. Sometimes they restart on their own again. They will always start up instantly if I turn the switch off and back on. The switch keeps power the whole time, so its not the switch or car cycling them off. If I connect that switch straight to an extra battery not in the car, they will flash for hours without stopping. Again, when connected to the car battery, the switch remains hot...just the strobes power wire goes dead. It cant be the strobes overheating because they would do it with whatever battery they were attached to. Its not in the car system, because the switch stays powered (confirmed) at all times. Ive tried 2 different switches and 2 different pairs of strobe lights with same re sults.

Are you running them through a relay? Should be and that is where I would look.
Does the manufacture say they are thermal protected??

each lite is self contained and thermally protected and requires no relay or controller per manufacturer. Like said neither should apply since they work for hours just fine if connected to an outside car battery, just malfunction connected to the car battery. Both are wired directly to positive and ground wires...not grounded thru car.

maybe some sort of weird capacitance build-up between the chassis and the stobes housing - maybe try mounting them differently??

Just guessing...

guesses welcome. Both lights are mounted on plastic panel at core support. Engine and compartment are cold as car is setting parked. After lights stop, I can switch the switch off and back on to reactivate them or even open the door to cause the dome lights to come on and they will operate again immediately.

Ive tried all the usual troubleshooting and still totally stumped as to why this happens only with the cars on board battery. Both the car battery and extra battery are identical and brand new so its not a battery fault. I have switched the two batteries with the same end results. Both of these batteries have identical test voltages and amperage with test instruments.

Do you have a battery drain preventer on there? Battery buddy or anything built into the factory system?

When you open the door, the system acknowledges that you are there and re-enables the power draw, or flipping the switch off to remove the load and back on and it works fine.

This was one thing I considered at first because it does have dual batteries with a isolator. It also has a factory system that shuts off all power if a battery falls below 11 volts. Both batteries maintain 13.4 volts. I discount this being a cause because the switch remains hot after the lights stop. Still 13.4 volts at switch input. 0 volts at switch output. I tried both a simple rocker and a simple toggle switch. Again remember there is no problem at all with them running off of another battery just setting on a fenderwell and the switch hot wire and ground wire connected directly to it.

[This message has been edited by rogergarrison (edited 06-30-2011).]

So when the strobes go dead the power wire from the switch also goes dead? is there a connection between the switch and strobes? have you checked for power right at the switch? are you using a VOM or a test light?

The red wire coming from each light is connected to the output wire of the switch. The switch input wire is directly connected to a constant hot. The black wire on each light is connected directly to battery ground wire. The red and black wires are the only wires on the lights. Housings are plastic and mounted on rubber isolator, then to plastic body panel.

Yes the switch output wire goes dead when the lights quit. Input voltage at switch was tested with voltmeter and testlight. A few times I noted the lights would come back on by themselves after a period without me doing anything.

[This message has been edited by rogergarrison (edited 06-30-2011).]

Almost has to be something else connected to the car system that is giving the strobe lights a fit. Maybe a momentary impulse or RF? Is the interval always the same or can you see any coincidence with anything happening in the car?

check the input to the switch with a test light not a VOM when the lights fail. then check the output of the switch with a test light. If the light lights up on the input but not ouput = bad switch. If it lights up on both connections check your ground connection. You said it goes directly to the battery is this the same battery where the hot wire comes from?

the lights are turned on and car is left just setting/parked with everything off and key removed. They will flash about 5 mins before shutting off. Pos and Neg wires are to same battery. Mutiple and multiple type switches were tried. All will work just fine with alternate battery. Tests were with both meter and test light.

Think im going to try a couple more tests with the vehicle battery connected to see what happens. One with a door left open to operate interior lights, and one with car idleing to see what happens after the 5 minute period.

[This message has been edited by rogergarrison (edited 06-30-2011).]

So the power into the switch is live but out of the switch is dead. Then the switch is bad. Try hooking the power and ground to the car battery not you external battery, just wires to the battery in the car, it should work the same. see if it does.

Since the stobes are connected directly to the battery (through a switch on the positive) it should rule out any problem with a battery run down circuit/etc. Try unmounting them from the frame (let them hang or something) and see what happens. Like I said, maybe some odd capacitance is building up between the strobe and frame and causing it to stop flashing - when you cycle the switch or whatever might be enough to disapate the charge.

It is an odd problem as a strobe is a very simple circuit as is self contained in the housing and should cycle as long as there is power to charge the internal capacitor - which is why I am thinking that there is some stray capacitance going on - doesn't happen with a stand alone battery because it is not connect to the frame of the car.

Ok you said guesses welcome

Have you tried a load equalizer?

[This message has been edited by Pappy (edited 06-30-2011).]

Load equalizer?

Well I turned them on and left the interior lights on with the door open. 5 mins later, strobes shutdown. Closed the door and opened it again, strobes came back on.
Ive tried a dozen different switches, so bad switch is ruled out. Ill try it with car running now. Then I will try just running wires to vehicle battery with no switch and unfused.

Again this one totally baffles me and im good at figuring out wiring problems in a limo where harnesses are arm thick. Ive built entire dashboards from scratch for custom RVs with everything imaginable installed in them.