Also, the charge lamp is on. I replaced the alternator and was told by
the tester it did not work at all. I get about 12.5v out of the alt
sometimes. Other times i will get around 14v. I think this is due to
On the drivers side fender, I have a silver box (think ford starter
solenoid), with three terminals on it. When looking from the driver
side, the left (grille side) has no wire attached. The Middle has two
wires, one comes from the alt, the other goes into the truck harness.
The right (firewall side), has one, that goes through a circuit
breaker, and into the coach I assume. I think something is wrong with
this setup, I am going out now to disconnect the coach and see if the
light turns off.
Any help would be greatly appreciated!
>I am currently battling a problem with my 1985 Dolphin RV w/ 22RE
>Motor & Toyota Truck Cab. If it is left for more than a couple days,
>it will kill the battery. Nothing is on.
>Also, the charge lamp is on. I replaced the alternator and was told by
>the tester it did not work at all. I get about 12.5v out of the alt
>sometimes. Other times i will get around 14v. I think this is due to
A bad alternator is probable, or it isn't wired up right - With the
engine running above 1800 RPM at fast idle (or while driving) you
should see roughly 13.5 to 14.5 volts at the battery terminals,
depending on the outside temperature (hotter = higher). That's the
proper float-charging voltage range.
If you are seeing 12.5V or below at the battery you aren't charging
enough and are most likely using power from the battery.
See if you have 13.8V at the alternator output stud at the same time
- the fusible link on the cable between the alternator output and the
battery could be blown. The fusible link is a 6" chunk of special
wire spliced onto one end of the cable that acts as a fuse if there's
a short circuit, like when a wayward wrench shorts the output stud to
>On the drivers side fender, I have a silver box (think ford starter
>solenoid), with three terminals on it. When looking from the driver
>side, the left (grille side) has no wire attached. The Middle has two
>wires, one comes from the alt, the other goes into the truck harness.
>The right (firewall side), has one, that goes through a circuit
>breaker, and into the coach I assume. I think something is wrong with
>this setup, I am going out now to disconnect the coach and see if the
>light turns off.
The silver cylinder is a continuous duty (*) high current (*) relay
(also called a solenoid or contactor) that charges the coach
deep-cycle battery when the engine is running, and isolates the coach
battery power from the starting battery power with the engine off.
(* - 'Continuous duty' is an important detail if you ever have to
replace it. Use a standard "Ford Starter Solenoid" that looks just
like it and it will overheat and burn out, almost certainly in under
an hour. More like fifteen minutes would be my guess, and it would
get hot and stink before that. And 'high current' meaning the power
contacts are usually rated at 100A+ continuous.)
If there is no wire on the big stud on the left (as you describe it)
I bet that's your problem - someone didn't understand what was going
on, and mis-wired the relay. The wire from the alternator output stud
is NOT supposed to be on the same relay stud as the coil power wire
going to the ignition of the truck...
This would effectively hot-wire the ignition circuit so the truck
ignition doesn't shut off - but even with a spark the engine will
still stop when the EFI cuts off the fuel supply, so you wouldn't
notice it. It would also explain the starting battery going dead,
because of the current drain from the ignitor module staying on...
The only other possibility is they got a batch of oddball relays for
cheap and didn't use the industry standard Single Pole - Normally Open
Charge Isolation Relay Functional Description:
The left side of the relay should be a large copper stud (5/16" or
3/8" threads) and that's supposed to go to the truck starting battery
+ terminal - but the alternator output stud works too, the factory
cable on the alternator goes through the engine harness and straight
to the battery, probably with a fusible link.
The two small studs (8-32 or 10-32 threads) in the center of the relay
will go to the relay coil, or if there's only one small stud the other
end of the coil uses the case ground to the truck chassis - make sure
that the case is properly grounded with tight mounting screws, and
that the fender itself is properly grounded.
The right side large copper stud relay terminal goes to a 30-Amp
self-resetting thermal circuit breaker, and then eventually to the
coach deep-cycle battery + terminal.
Dolphin (National) usually tapped the isolation relay coil power off
the ignition circuit hot wire, so it won't be left on with the key in
the "Accessory" position. The two batteries need to stay isolated so
you don't run down the starting battery with the overnight coach loads
- inside lights and the furnace blower.
And don't run the dashboard radio all night unless you have someone
rewire it with a switch to run off the coach battery when parked. The
starting battery is not a deep-cycle type, and can be ruined in under
a dozen deep cycles, like leaving the headlights on all night.
--<< Bruce >>--
>I didn't know the relay on the side had anything to do with ignition.
It does not, Dolphin added it - but they tap into the ignition power
circuit going into the ignitor and coil system to power the relay
coil, so it is energized only with the engine running.
>So you say the truck batt should be connected to the post on the
>grille side, the coach to the post on the right side. Does this mean I
>connect the alternator to the middle post? They all look identical. I
>don't think the unit is bad.
Depends on if it's a three-post or four-post. First, let's make
sure we're discussing the same thing...
See if your relay looks like this manufacturer's "Cut Sheet":
(Dial-up safe 476Kb)
There are other companies making the same design relays, some
overseas for cheap. But if you'll pay a few dollars more this is a
known quality source - Allied Electronics stocks them.
The two big posts 180-degrees apart are the power contacts in the
relay - one side to the truck battery + post /or/ the alternator
output stud, the other to the circuit breaker and back to the coach
The small posts in the middle are the relay coil - two posts (Type
3A or Type 4) and one needs to be jumpered to a ground point.
If you only have one center post means it's case ground and the
mounting point needs to be grounded - and you don't have a Stancor
relay, since they don't make a case-ground model...
NOTE THE NOTE at the bottom of the page: You have to use two
wrenches when working on this, if you don't hold the back-up nut you
can twist the contact in the case and destroy the unit.
--<< Bruce >>--
Disconnect the positive post of your starter battery,
Between the post and cable install a inexpensive VOM
set on high AMPS.
Disconnect fuses one-at-a-time to see which causes
the current leak to stop, and in this case, also disconnect
the incoming hot wire from your battery isolater (or
generator, etc.). Repair or replace the "bad" connection/
It's slow but accurate, and you may find other RV
components "leaking" current as well (heater, etc.).
We are not talking about the same thing I'm afraid.
I don't think my ford starter solenoid analogy was accurate, a friend
told me that was what it looked like, i assumed ford solenoids were
like that (Hey, I'm a toyota guy).
This picture should explain everything
Thanks for the help guys, keep it coming
>We are not talking about the same thing I'm afraid.
>I don't think my ford starter solenoid analogy was accurate, a friend
>told me that was what it looked like, i assumed ford solenoids were
>like that (Hey, I'm a toyota guy).
>This picture should explain everything
Oh sh*t, that's not a relay isolator, that's a diode isolator!!
I didn't know Dolphin switched over. Or someone tried to upgrade it
themselves and got it wrong... The best company for these is
SurePower, and NAPA carries them.
You need to leave the "To Alt" cable on the middle stud, and move
the "To Truck Batt" cable to the vacant end stud. And make sure the
power diodes haven't gone open.
There are two big power diodes under that black potting - Hot in the
middle, out at the ends.
And I'm betting whoever did this got it wrong, because many newer
alternators (Including 85 and later Toyota) fall into "Group 2" and
need a fourth wire from the diode isolator to the output voltage
"Sense" pin on the small alternator harness plug - go see the notes at
If you don't hook up the Sense pin to the starting battery so the
alternator sees the actual battery voltage the alternator puts out
13.8V at the output stud, and then you lose 0.7V to 1V going through
the diode in the isolator - and the battery never gets up to full
The sense pin input says "Bump it up - the battery only sees 13.1V!"
And when the starting battery didn't charge right, they put both
wires on the same stud and effectively bypassed the isolator to the
starting battery - and now the coach battery won't charge enough from
--<< Bruce >>--
Okay, tomorrow I will move the wire to the end stud and try again. I
still am trying to figure out the voltage drain.
Thanks for all your help.
It sees that the voltage coming back on the control wires is lower
than what's leaving on the Output lead to the battery, and that trips
the charge light.
>Just another Update. I researched it a bit and I think that I should
>splice in a wire from the center (alternator) terminal of the
>isolator, to the top (see diagram) pin of the plug. Someone let me
>know if this is right.
If the alternator in the truck is the kind that needs the external
voltage sense wire to put out the right voltage, you have the wrong
diode isolator - the fourth stud on the isolator is connected to a
third diode inside the potting compound, and the forward drop of the
diode (roughly 0.7 volts) fools the alternator into boosting the
output voltage by the same amount to compensate. Then you get the
13.8V you need /at the battery terminals/ to fully charge the battery.
Go to a local auto electric rebuilding shop that really knows their
stuff, and they can tell you. Or make a webpage with a few close-up
pictures and give us the URL address, and tell us the model numbers
stamped on the alternator case - one of the regular posters here used
to rebuild alternators, and he'll know from memory.
If you have to buy the 'right' diode isolator to get the sense diode
output, they're not cheap but not killer - $50-ish. If the one you
have was not damaged, someone with an older vehicle can use it. Older
cars sense the voltage from the small alternator leads, and do the
voltage boost by themselves.
--<< Bruce >>--