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Dashboard Alarm


electricjohn

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I am asking for someone to take a look under their dash and tell me how many wires are being used on the alarm. On mine the red wire is cut close to the horn and just the black and white wire are connected. The reason I am curious is because my oil pressure switch does not work, as a mater of fact, it was not even hooked up when I took delivery of my boat, and IIRC this should bring in the alarm. On my pre-delivery test ride, I was getting a constant alarm and the tech fixed it in about two minutes while the boat was still in the water. I think he just cut a wire under the dash to silence the alarm. Thanks in advance for any help you give me. Tomorrow I will climb under there again to continue traceing wires to try to figure this out. Hopefully a few '03 Monsoon owners can chime in.

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Electric,

Do you get any alarms? i.e., are you sure the beeper works? The reason I ask is that if you are getting other alarms and therefore you are sure the beeper is working, just not getting an alarm when you disconnect your oil pressure switch, the problem would not lie between the ECM and the beeper. It would likely be between the ECM and the Oil pressure switch.

When I was getting an oil pressure alarm, the way the technitian diagnosed the switch as the problem was to take the single wire (brown one, I think) off the switch and ground it out to the block of the engine. The alarm then stopped (engine was running). In other words, the switch sends a ground signal to the ECM when it sees a certain oil pressure (4 psi, I think).

I'm thinking, in order for your mechanic to quickly silence the alarm from the oil pressure switch, instead of just cutting the wire, he would have had to cut it and ground it out somewhere, and would have had to have done thjis between the switch and the ECM.

I don't know where the ECM is located, but perhaps you should follw the wire from the switch and see if you could find where it may provides it's signal to the ECM.

I'm assuming the problem is you do not get an alarm when you pull the single wire off the oil pressure switch...is that correct?

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RTS,

I did trace the wire (tan/blue) and it passes through the cannon plug and goes to the dash, where it is butt spliced to the alarm horn which makes no sense to me. The wire splicing to the other lead of the horn is purple/blk, which I believe is ignition (+) after the the safety switch. I could not find a tan/blue wire going to the ECM which is mounted on the back on the engine below the distributor but above the trans. As mentioned before, my oil P/S always reads open, and I have grounded the wire to it a few times with the engine running and got no alarm,IIRC. I was in two marine stores this past weekend and forgot to look for a Clymers manual. I am heading out now to double check my wire tracing from yesterday and run a few continuity checks. No battery in the boat yet so I can't shotgun around for 12 volts. I do get the beeps on key up, but I do not remember if they continue till engine starts or or it's just two quick beeps. I got two boats and they both have the alarm, so I might be confusing the key up sequence. Will post more later.

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For what it's worth, I'm looking at the wiring diagram in my Clymers for the MPI With MEFI 3 or MEFI 4 ECU (except 8.1 L models). I'm pretty sure that's what you and I have. Someone please correct me if I'm wrong.

Anyway, the schematic does in fact show a wire from the oil pressure switch directly to the ECU (Engine control unit) Don't know if that helps or not.

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Back again,

I traced out the wires a little more closely, and indeed, the wire from the oil P/S goes to the ECM. On this tan wire the blue stripe is spiraling. On the tan wire to the alarm it is straight. I did not look for the alarm wire on the ECM just yet, as I am doing multiple things in the boat getting it ready for summer. I pulled out the P/S and will take it in to work tomorrow to bench test it. The oil P/S wire is pin # 16 on the harness side of the starboard connector to the ECM. I also saw the trans T/S wire (tan/blk) and the water T/S wire (tan) going to the ECM. After I get a Clymers I am going to try to make a wiring diagram or schematic of the rest of the wiring of the boat. If I get that done, I will scan it and try to post it. Thanks for all your input. More tomorrow.

Edited by electricjohn
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Ended up buying a Mercruiser pressure switch which reads closed with no pressure on. It opens at 4-6 psi rising, and recloses at 6 psi falling, which I believe is what the old one should have done. After the install and connecting the battery I will test the alarm circuit out.

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