lhauto

Hi,
I'm new to this site and was hoping you guys can help me out. I'm a mechanic working on an electrical problem on emergency vechicles.

These vechicles have a rumbler mechanism that is activiated when the horn on the vechicle is pressed. When the horn is pressed, a 12v stream is released and the rumbler should be activated. Unfortunetely that doesn't happen.

I was also sure to check that 12v was actually being released when the horn was pressed and that work, but no rumble.

I tried to test it by putting the rumbler directly on a 12v battery and that seems to work fine.

Another test I tried and it worked was that I put a relay and used the 12v from the horn in order to activate the rumbler and it surprisingly worked.

Do you guys have any ideas?

BryanMD

I think you have found the problem.
Trace the original wire that fed the rumbler back and look for the relay that is supposed to be operating the rumbler.

__________________
March 2010: On the road with my RV. California is first primary destination then it is off to Eastern OR, Northern ID and Western MT for drycamping and fly fishing until Labor Day.

nap

or a fuse within that circuit.

micromind

Typically the horn button grounds the circuit. One side of the horn relay is always hot, and when the horn button is depressed it grounds the other side, thus completing the circuit.

You'll need to find the horn relay, and wire to the load side of it, or install another relay wiring it as above.

Rob

micromind

Double post.

Mackie

Yeah, anytime something doesn't work on one of my trucks, 99 44/100% of the time it's the ground...

__________________
2 Cor 13:14

Mackie

Hmmm.. I can't seem to find it on the Snap On site (might not be snap on), but a co-worker has a great automotive DC Voltage / diagnostic tester. It's got a clip on a wire on one end and a probe on the other. The digital read out gives you actual voltage. You can also give a voltage through the probe to check solenoids for example. It's really handy at about $150. This would be the perfect tool to diagnose your rumbler problem...

I'll get the info on it on Monday, if you'd like...

__________________
2 Cor 13:14

ohmer

If your still not sure, test the power at the wire termination point at the rumbler. This way you know for sure it has power to it or not.

__________________
http://www.ohmcheck.com

HighWirey

Good luck on repairing your emergency vehicles, but what is a 'rumbler' ?

Best Wishes Everyone

__________________
Be Safe Out there

randomkiller

Sometimes when using power switched through the horn you need to add better grounding on the steering column itself,I had that problem with some of the Fords in my FD/EMS depts.

__________________
A Veteran - whether active duty, retired, guard or reserve - is someone who, at one point in his life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including my life."

"One Nation Under God"

Mackie

The tester I referred to before is a Power Probe 3. It's very handy for Automotive electrical troubleshooting. Here's the link:

http://www.powerprobe.com/

__________________
2 Cor 13:14