Gauges react to blower motor

sailingseven · May 21, 2013

I have a 19' cuddy with volvo aq 131a/275 that when the blower motor is on the fuel gauge drops to by 1/2, charge gauge goes up, oil pressure jumps wildly, and the temp gauge shots to 250. When the blower is turned off everything returns to normal. What would you advise a starting point? checked connections and no corrosion or lose wires.

NYBo · May 21, 2013

Re: Gauges react to blower motor

Sounds like a missing "ground" (negative battery connection) for the gauges.

sailingseven · May 22, 2013

Re: Gauges react to blower motor

Thanks, will check when I have time this weekend.

Don S · May 22, 2013

Re: Gauges react to blower motor

Also sounds like the blower is hooked up to the ignition circuit. And that shouldn't be.
You need to hook the blower up to a fuse and switch on the accessory panel.

Auger01 · May 22, 2013

Re: Gauges react to blower motor

Check the ground for the blower motor and for the instruments. One of those has to be bad or missing I suspect.

sailingseven · May 23, 2013

Re: Gauges react to blower motor

Thank you

sailingseven · May 26, 2013

Re: Gauges react to blower motor

Okay I checked the boat over today. There are only 2 wires to the blower switch a purple and yellow. The other instruments have 4 wires due to lighting and each have a ground just like the diagrams that I found on the forum. The wire for the blower seems to be separate with an inline fuse and doesn't tie in with the the fuse block. I have yet to find where the blower has been wired for power or splice in. I will continue to trace it tomorrow. What are your thoughts?

sailingseven · May 27, 2013

Re: Gauges react to blower motor

The power is spliced in to the main power feed to the console, ignition, etc. Any thoughts?

NYBo · May 27, 2013

Re: Gauges react to blower motor

sailingseven said:
The power is spliced in to the main power feed to the console, ignition, etc. Any thoughts?

What he said:

Don S said:
Also sounds like the blower is hooked up to the ignition circuit. And that shouldn't be.
You need to hook the blower up to a fuse and switch on the accessory panel.

sailingseven · May 27, 2013

Re: Gauges react to blower motor

There is no accessory panel and there are no open slots in the fuse panel. Should I just wire the switch directly to the battery? any thoughts or ideas? Only accessories on the boat are a marine radio and fish finder both are wired directly to the battery.

sailingseven · May 27, 2013

Re: Gauges react to blower motor

The ground for the gauges are all good using my meter, but the blower has no ground attached. When the blower is turned on the voltage pulses(up and down by about 1 volt) to the gauges using the meter, but stays constant at the blower switch with no variation. When the blower is off the voltage to the gauges is stays level.

NYBo · May 27, 2013

Re: Gauges react to blower motor

If the only accessories are connected directly to the battery (with fuses, I hope), what IS connected to the fuse panel?

The blower is getting "ground" (battery negative) from somewhere, or it wouldn't work.

sailingseven · May 27, 2013

Re: Gauges react to blower motor

The fuse panel as best as I can see has a fuse for the gauges, an instrument light fuse, a trim tab fuse, anchor/running lights, bilge pump fuse, cigarette light / power point fuse,and cuddy lights/spotlight fuse which fills it up. The others do have inline fuses. After going back to out to the boat, I found that the negative wire to the blower has been slid into the cigarette/power point (- wire). I removed that - wire and ran a separate wire to the neg terminal (as a test) and still have the same trouble with the gauges reacting to the blower. Thank you for your help.

glenn property of pam · May 27, 2013

Re: Gauges react to blower motor

find how the gauges get to battery negative (via a buss) then use a lenth of wire and jump from there to battery negative and see if the problem clears.
You said you tested the ground buss with a meter. That is not a easy test unless you used a jumper wire connected to battery negative then read voltage between the known ground (the wire you are using for testing) and the buss.

kahuna123 · May 28, 2013

Re: Gauges react to blower motor

You have a bad ground to the dash. No question.

sailingseven · May 28, 2013

Re: Gauges react to blower motor

Thanks for your help. I crawled up in the area where the wires run and found the ground wire with some wear. I replaced it to the buss with 14 gauge wire from the - terminal. Now the only gauges that react are the temp and fuel. What would you advise next? Could the bare wire have damaged the gauges or senders?

glenn property of pam · May 28, 2013

Re: Gauges react to blower motor

clean the ground cable going to the battery. Both the temp and fuel have one thing in common they reference ground at the sensor. The sense wire goes to the sensor and is grounded by the temp sensor or the fuel float. If the ground is not referenced correctly then they start to play up and they also can act in reverse as a ground for stray power that should be going to a good clean ground. The fuel and temp maybe landed at a second ground buss near the back or they may be grounded near the dash. If you have one of the old style ground buss which is a strip of copper with screws in it you will have to remove all the screws and clean the strip then clean all the terminals. Even the battery negative post will need to be cleaned. 12v hates corrosion, dc can cause corrosion so its a bad situation that is fixed by cleaning all the terminals then applying a dialectic grease.

NYBo · May 28, 2013

Re: Gauges react to blower motor

1. The wire for the negative buss should be the same gauge as the positive, which should be 10 or 8 gauge.

2. The gauges should be getting power from the ignition switch, not the fuse panel.

sailingseven · May 28, 2013

Re: Gauges react to blower motor

Thanks I will get the 10 or 8 gauge tomorrow after finding out what the positive is. The gauges do only get power when the ignition is on. The buss is in the back of the boat on the opposite side of the gas filler. I replaced the wiring to gauges from the fuse panel (looked corroded/brittle) and cleaned the connections from the sensors, battery, and buss screws. They are working much better, but react slightly. I also noticed that the lines going from the buss forward are all different gauge wire shouldn't they also be uniform size & color?

kahuna123 · May 29, 2013

Re: Gauges react to blower motor

How to explain this? The blower motor needs ground. Where ever it is supposed to get it from. Which I am sure is somehow on the same circuit as the gauges. Its not getting it so via the gauges which use ground as signal. Thats why they go nuts. Look for where the ground comes from the back of the boat (batteries) and you find at least one black wire running up front. Check it and then see if the blower ground goes to the battery OR is pulled from the dash ground. You will find a bad ground somewhere.

When I had my shop I saw many lower units and $2000 shafts ruined in salt water with a similar problem.

Gauges react to blower motor

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