Low Voltage to purple wire feeding key ignition and dash gauges

[Shark_bait99]

Hello,

I have a 2004 Four Winns Sundowner with a 5.7 gi-e volvo engine and 1.51 sx-m drive.

Previously I had an issue with low voltage to fish finder causing crashes when engine cranked -solved by direct wiring to the battery

Now my new perfect pass cycles on and off when cranking or adjusting the trim, or even opening the engine hatch when the battery is somewhat discharged. The power to the perfect pass was patched into the purple wire on the back of the key ignition.

I tested the two battery voltages directly- 12.6v and 12.7v
At the fuse box under the dash and the components tied to it -11.9 v
The voltage at the key ignition, however is only 10.5v

I believe the fish finder was patched into this same purple wire as well leading to its problems.

I removed the gauges on the dash and found the infamous purple wire leading to all the gauges on the dash as well. They also test at a low 10.5 v.

My question is what are the possible causes of the low voltage to just this purple wire, but not to the fuse box? I have not been able to trace the wire back to the engine.

I think I can solve the pp problem by patching into the fuse box instead of the ignition, but why the low voltage???

 

[NYBo]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

The contacts inside of the switch may be corroded or, more likely given the load on them from all these devices, burned, creating high resistance/low voltage. However, I would start with the battery terminals since you also have low voltage at the fuse box. Only the gauges and perhaps the gauge lights should be connected to the purple wire. The ignition switch isn't designed for heavy loads.

 

[Silvertip]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

You have some wiring issues that keep getting compounded by sourcing off the purple wire. That line comes from the ignition switch and hence the engine harness. Accessories are to be wired to the fuse panel which is sourced from the "BOAT" harness. After you make the proper connections, determine why there is low voltage on the purple wire. The logic here is simple. You cannot get a full 12.6 volts OUT of the ignition switch if `12.6 volts is not present INTO it. Check voltage on the "B" terminal on the switch. If it is low as well, you need to work backward toward the engine as that's where the current is coming from. The fuse panel is fed directly from the battery via the smaller #8 or #10 gauge wires.

 

[Shark_bait99]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

Thanks for your help. I have found some ignition switch tests in the service manual so I will start there and attempt to trace the wires back.

One concern I have with the perfect pass is that if I wire it to the fuse box, it will stay on if I leave the battery on when at the slip (to keep the bilge pump active). There is an on-off button on the perfect pass, but the unit still keeps the display on. I guess I could just wire in a switch to manually cut the power to the perfect pass when at the slip, or just pull the power cord? I think this is why the installation manual suggests wiring it to the ignition system, so that it stays off when the key is turned off. Any other workarounds?

 

[NYBo]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

If the current draw on the Perfect Pass is low, say a couple of hundred milliamps, you can leave it attached to the ignition circuit. The other alternative would be to control it through a relay activated by the ignition circuit.

 

[Shark_bait99]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

relay activated by the ignition circuit.

Great idea! and a fun project too

 

[Shark_bait99]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

I completed the installation of the relay activated by the ignition circuit! Another fix thanks to iboats! Thanks!!!

The purple wire now receives more voltage. I also noticed that with the ignition off, I do get full voltage (maybe less 0.1-0.2V) to the fuse box and ignition. It is just once the ignition is switched on (but the engine is not started) that the voltage drop to the ignition and fuse box became evident. Is that just the resistance created by all the lights and accessories being powered up? There is also a burned out bulb on the dash that might be adding to the resistance?

With the relay now operating the perfect pass, I have about 11.6V in and out of the ignition switching & perfect pass with the ignition on.

My problem with the perfect pass appears to be resolved however while testing the alternator, I did not get any voltage out of the L terminal of the alternator while the manual suggested i should be getting 1-2V. The manual suggested I needed to replace the voltage regulator.

Without any other symptoms, should I just leave the regulator for now? Would I be experiencing any other symptoms if the voltage regulator is needing to be replaced. It seems I would have to replace the entire alternator ($500) as Volvo does not sell just the regulator. I did find an aftermarket regulator on ebay ($100 with shipping) so that might be an alternative?

Thank you!

 

[bruceb58]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

Putting the relay in is a band aid solution. You need to find where the voltage drop is. Out of curiosity, where is the voltage source for this new relay coming from? If I owned this boat and I found this relay installed, I would be removing it immediately.

When you do all your voltage measurements, make sure you use the battery ground as your reference point for your meter. You will obviously need a very long test lead for the measurements.

Depending on how you made your previous measurements, your ground could also be the source of your voltage drops so you need to check that as well.

 

[glenn property of pam]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

Depending on how you made your previous measurements, your ground could also be the source of your voltage drops so you need to check that as well.

This was my first thought. If you run a good know wire from the battery negative and connect the meter between the jumper wire and the positive do you still get the same results or is the voltage higher suggesting a dirty ground cable connection

 

[NYBo]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

Putting the relay in is a band aid solution.

It's only a band-aid in this case because we didn't get the info about the alternator/regulator problem. But it's a perfectly acceptable way to take a load off the ignition switch if one insists on having an accessory be powered in concert with the ignition; the Perfect Pass is one for which it makes sense (if it draws significant current).

 

[bruceb58]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

It's only a band-aid in this case because we didn't get the info about the alternator/regulator problem. But it's a perfectly acceptable way to take a load off the ignition switch if one insists on having an accessory be powered in concert with the ignition; the Perfect Pass is one for which it makes sense (if it draws significant current).

I agree with what you are saying. Nothing wrong with powering the one accessory off of the new relay but the bigger issue is the voltage drop which he needs to find.

 

[Shark_bait99]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

Thanks for all of your input. When the ignition switch is off, I have full voltage (12.5V) to the fuse box and the ignition switch. It is only once the ignition is switched to on, but the engine is not started, that the voltage at these two points drops to 11.6V. Is this not normal, with all of the accessories powering on, that the circuit would develop some resistance and create a voltage drop?

Bruce - The new power source for the relay is a previous splice into the VHF radio line which is fed from the 3A fuse in the fuse box. The perfect pass also has an inline 3A fuse in the wiring so this seemed like a good match as the VHF is not used by us land locked, freshwater folks.

 

[bruceb58]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

No...not normal.

What are you using for your ground reference on your meter when you do the measurements?

The relay is probably ok. Once you figure out your voltage issue, you probably won't need it but I don't see a reason not to leave it.

 

[Shark_bait99]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

No...not normal.

What are you using for your ground reference on your meter when you do the measurements?

The most accessible ground that I have been using is on the back of the stereo controls under the dash

 

[bruceb58]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

Personally, I would get a long test lead and make sure you don't have drop between your ground at your dash and your battery or use the battery as your reference.

You need to eliminate the ground being an issue first.

 

[Fun Times]

Re: Low Voltage to purple wire feeding key ignition and dash gauges

Hi there Shark_bait99, thought maybe you'd like to read this members thread as it pertains similar characteristics as what your going through near the end of the thread on page 2,

http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/loss-spark-under-load-628672.html