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Low Voltage

Jons

Member
Hello I'm getting a low voltage from one of my 130 Honda motors, the battery is at 12.8 but volt gauge only read 9 to 10 volts. Any idea where to check at motor, plug or fuse. Thanks Jon
 
First remove connectors from battery and thoroughly cleanbattery posts and connectors. Then with engine is running at 1000 rpm connect avoltmeter to the battery terminals. You should be getting between 13.8 and 14.6volts. If so, then you have a problem with the gauge, gauge wiring, or ECM.
Remove gauge and thoroughly clean connectors. While gauge isremoved, direct wire it to a power source (boat battery or separate battery)and compare its reading to your voltmeter. They should read the same +/- a halfvolt or so. If not, replace the gauge. If they do read the same re-connect thegauge and retest. If it is still reading too low, then you have a problem withthe wiring to the gauge, or the ECM (electronic control module.) The usualproblem is that the gauge ground wire gets corroded, so check that first. Ifstill not right, disconnect the signal (S) wire from the gauge, and with enginerunning at 1000 rpm, use your voltmeter to test the voltage between the signalwire and a known good ground terminal. (Note that the voltage coming out of theECM may be a bit lower than the voltage coming directly off the alternator tothe battery – I have no idea why that is, but on my 225 the alternator voltagereads 14.6 and the ECM voltage reads 13.8.) If you are still getting a lowreading, then you have a problem with the ECM or the wiring from the ECM. Atthis point, you will need to do some testing on your ECM, so hold that offuntil you determine that as the problem
If you are not getting 13.8 to 14.6 volts at the batterywhile engine is running, then remove connectors to the alternator, thoroughlyclean and reconnect and re-test. Not sure how your 130 alternator is set up,but if it has a separate ground wire, test the resistance between the batterynegative terminal and the alternator ground terminal, it should be very nearzero resistance. Test the resistance between the battery positive terminal andthe alternator positive terminal. It should also be very near zero resistance.
If you still have low output from the alternator, then you likelyneed to replace or rebuild it.
 
Thanks for the quick help. The gauge every now and then will read 12 volts, checked gauge and its showing the right voltage. Did change alt same thing. With the help from post should find it. Thanks again. Jon
 
Hello, Still chasing this one year later. When I put in salt water everything works fine, as soon as I go back to fresh water reds low voltage again, any ideas.
 
Are you actualy putting the boat in fresh water, or are you talking about using muffs connected to a fresh water hose?

I'd like to see Mike, Jimmy, or Chris jump in on this one. Generally, the salt water like an electrolyte, completing a connection that is otherwise weak. Generally that is very bad for your motor and will eat up your sacrificial anodes. However, I do not see how that should make a difference unless there is a wiring problem with your tilt-trim motor.
 
Thanks, I run the boat on the Caloosahatchee River Fort Myers area which is fresh water but when I go into the Gulf everything works right. Why do you say the tilt and trim motor. ?? I'm thinking a grounding fault but the main ground is clean and tight. Thanks again
 
"Why do you say the tilt and trim motor. ??" The tilt-trim motor is the only electrical device exposed to water and would provide a path for current into your electrical system. That is a real long shot, but the fact that everything settles down when you are in saltwater, is strange, indeed. Time for Professor Jimmy to jump in on this one. Here is a random thought - when you are going out the river, you are likely in calm waters, but when you hit the Gulf, more likely than not you are experiencing some chop. Could it be that there is a loose or corroded connection that gets a better connection when you experience the bouncing around from the chop?

I agree that it is likely a ground fault. Since you are not having any problems with cranking the engine, I suspect that your main battery cables are okay. I assume you are still basing your analysis on what you are reading from your voltage gauge, correct? Did you go through the procedure I initially posted to eliminate any problems with the gauge? If not, you should do that first.
 
my approach would be this...get the failure on the system where the battery voltage reads good and the meter reads low....place the voltmeter across the battery terminals and verify your 12.8 reading..leave the positive lead on the battery..move the negative lead to a metal part of the engine...a head bolt or anything that does not have paint insulating it from the meter lead...if you have 12.8 there then the ground is good...if not you have a drop in the negative lead to the motor...if this reading is good i would then hook the meter lead back to the negative post on the battery....verify that the reading is still good across battery...then move the positive meter lead to the positive post on the starter solenoid and see what you read...i think this will be good also because you didnt mention starting problems....but be alert for any change in reading..even a .2 or .3 change will be an indication of a problem...if there is any change in the reading from the meter reading directly across the battery your problem is in the positive feed...if all that is good lets move the meter to the meter thats reading low...we want to make the same decision there...is the problem in the positive feed or the ground side is the question...verify that you have a good meter(boat meter) by taking a reading across the terminals on the meter..then go from there to make the same decisions we made on the motor end of the system...if the reading is low as expected then move one lead at a time back to the battery posts to decide where the voltage drop is... either the positive or the negative (ground)feed...you should at some point have the bug trapped and know what circuit is dropping the voltage...if the problem has been going on for a long time as you indicate i would not do anything to run the problem away at this point....take your knife and skin off a little insulation if needed to get a meter lead to the wiring if necc etc...just remember to tape it back up when you are finished....try to get it down to a specific wire or a plug etc before you start moving things around and possible chasing the bug away...
the salt water bit is because the salt water is a conductor....fresh water is an insulator as far as current is concerned....
you have a braided wire going from your power trim to the ground on the motor...make sure this wire is good...its located on the motor in the back above the keel of the boat...i have heard but never experienced that this wire will burn open on a reversed battery connection...
you will probably run into a problem with meter leads being too short to reach the console and the motor/battery at the same time...you can jury rig with some wire or buy a set of long leads...they aint cheap...
good luck and get back to us please....
 
i would write down the readings and where the meter is connected as i go...accurate readings...down to the decimal point.....it will help us and you on later decisions....the circuitry here is simple but all of us know that some problems can be confusing.....that boat meter could be picking up its ground thru feedback through another instrument for example.....just take your time and get back to us if needed...
 
Thanks again for the quick help, I'm the weak link here. The change happens the instance boat goes into different water, has not read right for two months than when backed boat into salt water and started it was fine. Reads perfect in gulf than go thru lock into fresh water and it's back to low voltage which also makes fuel gauges read lower than they are. Jon
 
I'm headed to the Keys for a World Cat Rally, will check this as soon as back. Thanks again for all the good help. Jon
 
More questions than answers....

Is there a ground buss of any sort between the grounds of the batteries of the two motors?

Do the voltmeters read differently if the motors' key switches are just turned to on...without the motors running? When in freshwater...If so, then testing could be much easier.

Have you tried just running a jumper wire from the ground on the failing gauge cluster to the gauge cluster of the other engine. A simple jumper wire with alligator clips should make a good test. Just make the test then remove it. If the voltmeter reads correctly, then you know that the saltwater is probably improving the ground between the two engines.

If there is a ground buss between the two motors, make sure everything is clean there. Just thinking, what is the salt water touching to make a difference in current flow? I am pretty sure the World Cats are fiberglass, so the boat is not a factor in this equation. As others have mentioned, the braided wire connecting the motor mount to the engine frame might be a source of interest if not there or corroded. The salt water will act as a conductor between all lower parts of the engine and well as the other engine. If the bonding (if any) between the engines has an issue, then the salt water will cover that up.

Have you checked the 14 pin round connector at the engine at the end of the wiring harness? Disconnect it and check the pins connected to the black wire for corrosion. Also make sure that the pins are not pushed out of the connector.

Also check where the grounds of the wiring harness on the engine all come together. There are two connections. If you are on the port side lower front corner of the engine block, there are two screws that fasten the ground wires to the block. They are about even in height with the fuses. I can not remember if you have to remove the black plastic piece (muffler) on the front of the engine to get to them. Make sure there is no corrosion there and the wires are not frayed.

Bottom line, I am with the rest of the guys in thinking there is a grounding problem....you just have to find where. As long as you can test with the engines not running but key switch on, then you can use a small wire to jumper any place that you think might be questionable without worrying about high current flow. Do not try to start either engine with a temporary jumper in place, it might fry it. I say that because we do not know where all the current is going at this point.

Mike
 
i think it is failing with just the key on from his initial entry...he is just reading a fully charged battery...12.8....i forgot to ask him if the tach for that engine is operating correctly.....interesting little problem....
 
not really knowing the physical distribution of the 12 volts under the console and not knowing if the tach ever fails its hard to say but if the tach works correctly i would speculate that he has a bad crimp under the console or connection to the meter...if he has no crimp in the wiring and the 12 volts goes to his voltmeter first and then there is two wires on the terminal and the other wire goes to the rest of the instruments then he has a bad meter connection or a bad meter..and i doubt bad meter...from what i read the boat has run like this for a year or more and this is the only failure he has given us..of course it could be a bad crimp or something in the ground under the console also...how the tach is doing is a key question...
 
Ok new updates, hull is fiberglass, the low voltage is on port motor Honda 130 4 stroke which starts and runs fine. Have 12.8 volts at battery, 12.8 volts at starter motor, two grounds on motor large cable from battery and a small wire from black box both right next to each other port side low. When I turn keys on to start motors Voltage is 12.8 on Starboard motor and shows low or no Voltage on port motor. With boat on trailer turning port motor key, it doesn't show any voltage at all, back boat into fresh water at the dock it shows 10 volts, when I put boat in salt water before I even start motor as soon as the key gets turned to start it reads 12.8 been working on this by myself with no helper so going little slower. Thanks again for the help. Jon
 
Do I understand correctly that your problem port engine starts and runs well, but your voltage meter and electronics don't work properly until you hit salt water - correct? If so, look on your transom and under your boat and see if someone installed a grounding plate. Often times they are installed for SSB radios, Loran devices, or lightening protection. Thus, your electronics package will also be grounded to the ground plate. If there is one in place, then what very well could be happening is that the main ground wire to your electronics has failed, but when you hit the saltwater, the circuit is completed between your engine ground and the ground plate via the saltwater, then providing a proper ground to your electronics. If that appears to be the case, then run a jumper wire from your battery ground to the main ground on your electronics package at your consol. If that clears up the problem, then look for corroded ground connects in and around your instrument package, or replace the main ground wire from your battery to the instrument panel.
 
agree that it is a grounding problem all the way with the new info....we cant get away from the fact that both motors work correctly so that points to a problem with the ground to one instrument panel..and the fact that it shows zero makes me think there may be no ground at all from the panel to the port engine..it may be picking up both the 10 volts and the 12.8 from the water connection to the starboard engine.....it could very well be the ground is open from the battery to the instrument panel grounding location..how this connection is made is impossible to say because we dont know the physical layout..but if i am correct in saying the ground is picked up from the other motor when in the water then the ground tie in could be anywhere including under the console or a terminal block or grounding plate in the battery compartment etc.....basically i agree with CHawk...looked at your profile CHawk..WELCOME HOME !!!!!
..
 
Hi,

I didn't read all posts so I hope I'm not repeating... Had same issue today, Honda Volt meter was reading low so I used a multi meter on the back of it and meter was fine. Gauge was off.
 
Papyson - Thanks. Did you also have occasion to have visit the land of the little green snakes?

Anyway - I totally overlooked the fact that the second (starboard) engine could also be acting as a ground plate as long as each of the engine batteries is sharing a common ground. I think the analysis is still valid. So, Jons, that narrows to problem to the fact that your ground to the port engine instrument cluster has failed somewhere. Since you can start the engine from the key panel, that ground must be okay. As I suggested above, hook up a jumper cable to the battery ground, or a good known ground source, and connect directly to the ground on your instrument panel, then see if that lights up you gauges when the key is turned on. If so, then use a process of elimination to figure out where the fault is. Likely a disconnected or corroded connection somewhere in there.
 
Got it chawk man, thanks for all the help from everyone. Ran a jumper from port battery to main ground buss and works fine, tomorrow morning will run new ground wire. Really appreciate all the help in solving this ongoing problem. Jon
 
Great! Glad you solved it. Just for forensic research, you may want to take the time to carefully remove the old ground wire and try to determine the nature and location of the exact failure so that when it happens again, you will know exactly where to look.
 
Today will be putting on new ground from battery to buss bar. One last update, hooked up jumper cables from port drive to starboard drive and with boat on trailer voltage is right, which means when it was in fresh water it was grounding back to other motor, and showed 10 volts but when in the salt better flow and read 12.8 volts. Thanks again Jon
 
i forgot what problem we were working on but i know it was dual honda setup and i remember there was a ground wire between the port and starboard cluster under the console that we removed temporarily in process of shooting that problem.. hondadude may be familiar with that wiring...and the fact that the ground was completely open could point to a crimp tool being used under the console in the wiring...i hate crimps with a passion...have had to rewire a couple of my own boats for that reason..i worked for a warrant in the old navy and it cost you a stripe if he caught you in possession of a crimping tool..
 
Papyson - problem solved. Ground wire from port engine to instrument cluster had failed, but when he hit saltwater everything started working. He was stealing the ground from the starboard engine via electrolysis through the saltwater.
 
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