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 > Dashboard Alternator light

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theoldwizard1

SE MI

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Posted: 08/01/21 03:29am Link  |  Quote  |  Print  |  Notify Moderator

eric1514 wrote:


What I don't know. I'm still not convinced that Ford didn't program the idiot light to show an over voltage condition.

I disagree !

As stated, the PCM controls the voltage. If it is not within the range of the desired voltage, the light come on. That range is very small.

StirCrazy

Kamloops, BC, Canada

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Posted: 08/01/21 06:45am Link  |  Quote  |  Print  |  Notify Moderator

I just went through somthing like this on my truck. one of the two wires that controle the voltage between the voltage regulator and the PCM broke and the altanator defualted to 14.6V which its suposed to do but it also throws a code. this voltage for two long will kill a normal starting battery which is why they dont just default to that voltage. do you need your starting batteries linked to the house batteries when your camping? I would just simpaly put an isloater between them that will let you charge the house batteries while your driving but not charge the starting batteries from the solar.

Steve


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BFL13

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Posted: 08/01/21 07:43am Link  |  Quote  |  Print  |  Notify Moderator

theoldwizard1 wrote:

eric1514 wrote:


What I don't know. I'm still not convinced that Ford didn't program the idiot light to show an over voltage condition.

I disagree !

As stated, the PCM controls the voltage. If it is not within the range of the desired voltage, the light come on. That range is very small.


Suspect it is the light circuit getting grounded ( he says, "earthed") when solar comes on or getting a high resistance from the solar coming on, which will make the dash light come on it says here:

https://www.howacarworks.com/ignition-sy........oubleshooting-the-ignition-warning-light


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eric1514

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Posted: 08/01/21 07:59am Link  |  Quote  |  Print  |  Notify Moderator

theoldwizard1 wrote:


I disagree !

As stated, the PCM controls the voltage. If it is not within the range of the desired voltage, the light come on. That range is very small.


Hold on. You and I are in agreement...mostly. It turns out that 14.6v is not necessarily "too high" but more like, "too high given the current conditions".

I did a bunch of reading last night and some this morning and I learned that the alternator will put out more than 14.6 volts when it's called for, like in the case of a severly depleted battery. In fact, 14.7 volts is the target of one of the tests used to determine if the alternator is good. But the PCM looks at things like battery voltage and engine RPM and if it determines that the alternator voltage is too high for the speed of the alternator and the condition of the battery, it will illuminate the charge light because it thinks the alternator or the voltage regulator is not doing its job. That's what I think my problem is. Given a fully charged battery and moderate RPMs, the PCM is concluding that 14.6 volts is out of range for the conditions at that specific time. It is mistaking solar output for alternator output.

That's my story and I'm sticking to it.

What I need to do is change the solar output voltage and see if I can turn off the light. If that works, I'll live with it. Less than ideal, but it'll be OK. What I'd like to be able to do is turn off the juice going forward to the chassis battery from the solar panels while I'm driving and only then, but that's above my pay grade.

To be continued...

* This post was edited 08/01/21 08:15am by eric1514 *


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dougrainer

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Posted: 08/01/21 08:23am Link  |  Quote  |  Print  |  Notify Moderator

14.0 and over WILL cause both a FORD and a Monaco Roadmaster chassis dash Alt Idiot light to come ON.
Monaco has a fix for this as this ONLY happens when you drive and have engaged the Genset and the Inverter/Charger goes to BULK(higher voltage) charge. A few ways to stop the dash light. ADD a higher amp draw while driving. Turn the Headlamps ON and the Dash AC . Usually this will cause the voltage to drop enough to turn on the alt light. WAIT until the Inverter/Charger system drops its bulk charge(usually less than 1 hour) and the light goes out.
OR, as Monaco did, install a Bosch relay into the Ign retract step circuit hot wire and the Hot wire that engages the dual charge solenoid in series with the Genset hot hour meter wire. What Monaco did was WHEN you turned the engine ON, the solenoid joins both battery banks. So to stop the higher bulk voltage causing the error, they had us wire in that bosch relay so that when the relay saw the Genset hot wire it opened the 12 volt wire to that dual solenoid. This did not cause a problem as when in transit, if the Genset was ON, your coach batteries were charged by the Inverter Charger. When in Transit and Genset OFF, that Bosch relay transmitted the 12 volt signal to the dual solenoid to allow the engine Alternator to charge the coach battery banks. Monaco actually has a TSB for this from the early 2000's. Last there is NO problem caused by that higher voltage other than the light being an annoyance when driving. Doug

eric1514

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Posted: 08/01/21 08:58am Link  |  Quote  |  Print  |  Notify Moderator

dougrainer wrote:

14.0 and over WILL cause both a FORD and a Monaco Roadmaster chassis dash Alt Idiot light to come ON.
Monaco has a fix for this as this ONLY happens when you drive and have engaged the Genset and the Inverter/Charger goes to BULK(higher voltage) charge. A few ways to stop the dash light. ADD a higher amp draw while driving. Turn the Headlamps ON and the Dash AC . Usually this will cause the voltage to drop enough to turn on the alt light. WAIT until the Inverter/Charger system drops its bulk charge(usually less than 1 hour) and the light goes out.
OR, as Monaco did, install a Bosch relay into the Ign retract step circuit hot wire and the Hot wire that engages the dual charge solenoid in series with the Genset hot hour meter wire. What Monaco did was WHEN you turned the engine ON, the solenoid joins both battery banks. So to stop the higher bulk voltage causing the error, they had us wire in that bosch relay so that when the relay saw the Genset hot wire it opened the 12 volt wire to that dual solenoid. This did not cause a problem as when in transit, if the Genset was ON, your coach batteries were charged by the Inverter Charger. When in Transit and Genset OFF, that Bosch relay transmitted the 12 volt signal to the dual solenoid to allow the engine Alternator to charge the coach battery banks. Monaco actually has a TSB for this from the early 2000's. Last there is NO problem caused by that higher voltage other than the light being an annoyance when driving. Doug


Thanks!

The Monaco solution is so far above my abilities I'm embarassed, but turning on the headlights is brilliant. Even I can do that. In fact, if I drag my TOAD along I have to because I wired the TPMS repeater into the taillight circuit of the coach.

Ignoring is also an option. My OCD might preclude that, but it's something to try. The solar controller will drop out of bulk in 2 hours and into absorbtion at 13.8v and that should solve the problem. That's just another test I'll have to perform, but I agree, 14.6 volts is not a bad thing.

Thanks again,
Eric

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Posted: 08/01/21 09:16am Link  |  Quote  |  Print  |  Notify Moderator

As others have stated, I don't think you actually have a problem, or need to change anything to fix it. The alternator light is coming on, because the 12V bus voltage does not agree with what the ECU expects from the alternator. As you know that this higher than specified voltage is coming form your house batteries, and not from a fault in your alternator, you can safely ignore the light.

BFL13

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Posted: 08/01/21 09:41am Link  |  Quote  |  Print  |  Notify Moderator

Doug has put us out of our (and his!) misery. I ran a test with our newest vehicle, a 2016 Ram Promaster City van.

Idling and warmed up showing 13.79 voltage at battery with multimeter, no battery dash light.

Using adjustable voltage deck mount converter with clamps on the wires (PowerMax LK) I set voltage to 14.6 and clamped on. Nothing happened, no light.

Cranked the voltage up slowly and the engine stumbled but kept running when voltage was 14.99, looked at dash and the battery light was on bright red. Disconnected charger and battery voltage back to 13.8ish but light still on.

Turned off the ignition and restarted. All normal, no red battery light

I am not sure it is ok to keep driving with the light on from over-voltage like that, seeing how mine had that engine stumble (almost died then back on full) when the voltage reached whatever it didn't like, but I have no knowledge of all that.

theoldwizard1

SE MI

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Posted: 08/01/21 09:58am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:


Suspect it is the light circuit getting grounded ( he says, "earthed") when solar comes on or getting a high resistance from the solar coming on, which will make the dash light come on it says here:

https://www.howacarworks.com/ignition-sy........oubleshooting-the-ignition-warning-light

That diagram is OUTDATED by at least 20 years! No cars work that way any more.

The PCM tell the alternator/regulator to raise or lower the voltage. If the desired voltage can not be achieved, the PCM sends a message to the cluster to turn on the light.

RLS7201

Beautyful Downtown Gladstone, MO

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Posted: 08/01/21 02:01pm Link  |  Quote  |  Print  |  Notify Moderator

Well now that every one is through guessing, here is what's happening with your alternator light.
The alt light gets a + voltage from the dash when the key is turned on. The light sees a - voltage on the other lead from the alternator when the engine is NOT running and the alternator is NOT producing. When the engine is running and the alternator is producing, the light on the dash sees a positive voltage on both leads and the light is off.
Now when you solar panels gets the line voltage above 14.6, the alternator regulator shuts the alternator down and the dash light sees a - voltage on the lead to the alternator and turns on.
Nothing wrong with you MH charging system.. The light is doing what it should.

Richard


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