Getting Engine Alarm Buzzer to Work

[sail sfbay]

All four helm alarm lights turn on when I turn on the engine switch on just prior to starting both Volvo Penta TAMD70E engines. However, only one (1) helm alarm buzzer operates. All the instruments work after turning on the engine. This condition has been like this since I purchased the boat last November. I replaced the alarm control unit and buzzer at the 3 stations with OEM parts and still not resolved. I had a marine electrician and mechanic look at it without success and have now scheduled a appointment in mid-July with a Volvo Penta dealer. Is there an something I am missing or do I just keep investigating?

[wingless]

Assuming one light each for oil pressure and water temperature (or generator) for each engine.

Are there also four piezo buzzers, or just one?

If just one, then there must be an electrical logical OR circuit to cause a single buzzer to sound when any (or more) of the four monitored circuits alarms.

[sail sfbay]

Thanks for your post. 4 buzzers, one for each helm engine switch, 2 upper and 2 lower helm.

[wingless]

The engine alarm switch connects that wire to ground during an alarm condition.

Prior to starting the engine the low oil pressure switch will cause that wire to be grounded.

An alarm light, or an alarm piezo buzzer, will have one wire connected to +12V, active when the engine has power and the other wire connected to that alarm wire.

The symptoms indicate that the lights and one audio alarm is correctly wired. The others are not yet wired correctly.

[sail sfbay]

wingless........really good explanation. My electrician will be on my boat on Monday so will discuss this with him. As a backup, I scheduled a local Volvo Penta mechanic in mid-July.

[Snore]

Before I assumed bad wiring, I would check the sensor.

With the engine off, check for continuity between a known ground and the switch. If there is continuity, then go for a known 12vDC source to the switch. You should get 12vDC.

If that checks out, with the engine off, run a long jumper from the sensor to the alarm. Check for continuity on the ground. If you cannot determine pos/neg check both. Since the engine is off the pos will be dead.

If you have continuity from the sensor to the alarm, the fault is on the pos side. It is feasible that the switch is bad and bot feeding power to the alarm.

Seems exceedingly odd that a competent mechanic and competent electrician could not solve this.

[sail sfbay]

wingless and Snore........thanks!! Will advise my electrician of your recommendations.

[Dsanduril]

Each engine has two control stations, one at upper and one at lower helm station?

If that is correct then there has to be a Volvo harness extension somewhere that includes a splitter to send the signals to both control stations. If you can access the splitter for the engine with one buzzer working then I’d try swapping the cables for the two helm stations. If the same buzzer still works then the problem is in the control station that is not buzzing. If the other buzzer activates then the problem is in the harness to the non-working station.

For the side where no buzzer is working it is more difficult, if you could swap cables for port/starboard (if located close enough) you might be able to use similar logic. Otherwise, my suspicion would be at the engine or in the main harness before the splitter.

[sail sfbay]

Dsanduril..........yes, two control stations for each engine, one at upper and one at lower helm station (2 engines with alarm switches at each of the 4 control stations. Taking more notes. Thanks!!

[Lake-Effect]

My friend's boat has a buzzer that won't quit. Wanna trade?

(his sensors are all ok, so there's a wiring fault or a logic problem, probably in the control unit) [/derail]

[Dsanduril]

Just looked at the wiring diagrams, whether or not you can swap cables will depend on whether or not you have two “A” panels or an “A” and a “C” panel. If there are key switches in both panels then the wiring is the same, but if the key is only in one panel then the aux “C” panel is different.

In both panels (A and C) the buzzer is connected to pins 5 (positive, blue w/ red stripe) and 6 (negative, white with black stripe). Both + and - pass through diodes from the warning lamps to provide the OR function from the warning lamps.

I’d try a DVM at the buzzer, if you see +12V on pin 5/blue-red when the warning lights are lit then the diodes on the + side are OK. If you don’t see 12V then I’d start looking at those diodes. Similar testing on the negative side.

I’d also confirm the buzzer itself is working (even though just replaced) by testing it with power directly.

The wiring diagrams are in the owner’s manual available on the VP website. This link may work, otherwise you may have to navigate through the menus.

https://www.volvopenta.com/en-us/ser...and-handbooks/ use “Product Designation TAMD70E (INB)”.

[sail sfbay]

Dsanduril.............thanks again, this is very helpful. I have the owner's manual, looking at it now, and will take a close look at it with my electrician on Monday as I am chemical engineer and I get lost with complicated wiring diagrams.

[sail sfbay]

Today may marine electrician was able to get the buzzers working by chasing down and repairing some wires and some connections. One interesting result at the 3 helm stations with new / latest generation alarm control units is that there is a 10 second delay vs. instantaneous (like the original alarm control unit alarms on the 4th helm without original alarm control unit), before the the buzzer alarm sounds after turning the ignition switch to on, just prior to turning the switch to turn the engine on. The delay on the latest generation alarm control units may be designed that way to allow the glow plug to heat up.