code 3 siren help

[vt4runner]

it worked when pulled from previous vehicle. powered it up today and nothing. all i get is a quiet sqeaking noise from the box, nothing from the speaker. unit is a code 3 model3692. speaker is a whelen SA314. any ideas on how to start diagnosing this. checked the fuse, intact, all circuitry appears intact. thanks for any help.

[john9912]

Usually if you hear siren tones at the siren itself, the amp is working and problem lies with the speaker or speaker wiring. Check your wiring then check the speaker on another siren and check that siren with another speaker.

[jackhackett]

A quick way to check it is put a multimeter set to AC volts on the siren output terminals, a 100W siren will show somewhere around 30 volts AC. If the voltage is good, check for an open circuit on the speaker or cable.

If you read little or no voltage try disconnecting the speaker cable, but don't run the siren this way any longer than needed to get a measurement. If you then get good voltage on the output terminals with no speaker, check for a shorted speaker or cable. The normal speaker resistance is low, maybe around 5 ohms, it shouldn't be close to zero.