Engine voltage/charging problem

[bwatters60]

Started the Roadtrek (2008-210P on an '07 Chevy 3500 chasis) last week and the battery indicator stayed on, and volt meter read about 10 volts. Long story short, the alternator tested bad (120k mi) so I had it rebuilt. The alternator shop informed me the voltage regulator was bad and suggested I check the battery. The battery voltage was 12.35 and tested weak so I bought a new battery. And since the circuit breakers attached to the isolator appeared to be original (and exposed), I replaced them. The voltage on the first start was normal (around 14). However, on subsequent starts the low voltage symptoms reappeared. I disconnected everything and tested the isolator (Powerline 33-301). It tested good. Reconnected everything and started the engine and learned I wasn't getting 12 volts to the E post (exciter to get the alternator started). Installed a new relay (NTE R51-1D40-12F). Again, same results - battery indicator goes off and engine voltage meter is normal on first startup, subsequent start ups it drops to about 10 and the battery indicator stays on. If I connect 12v directly to post E before starting or during running, the battery indicator will go off and voltmeter returns to 14v (voltage is also normal if I connect the B1 post wires, which include the engine battery, to Post A which terminates the wire from the alternator) . So, I tested the yellow wire feeding the relay from the ignition and no voltage (with engine running). Fuses in the fuse block labeled ignition (qty 2) both check good. So my next step is to trace the yellow wire that disappears into the big flex tubing. I hate to disturb wiring or the fuse block. Any suggestions? Thanks in advance.

[markopolo]

Interesting photo.

I can't help but thought I'd mention that I don't recall ever seeing a relay used with one of those isolators. Could it have been added by an owner at some point?

I thought Roadtrek had switched to using battery separators by '07. Maybe '07 was the changeover year.

The '04 Roadtrek I owned had a Hehr Powerline isolator but I don't remember seeing a relay there.

[booster]

A couple of questions first.


2007 was in the changeover period on the alternators from internal regulation to computer controlled, we have a 2007 chassis that has an internally controlled regulator, meaning the rest of the connections really shouldn't be doing much unless the unit sees and ignition off, I think. You could have a bad connection somewhere from the ignition.



Can you confirm the 2007 Chassis and see if it has an internal regulator in the alternator. If it is a 2007 with an internal regulator, my factory service manual will apply and I can get you a scan of the page with the wiring diagram so show the exact wiring, of course without the isolator or coach stuff.


The internal regulators they used were "semi" smart in that the will turn down the voltage based on duty cycle, time, and temp I think and have been known to fail. The regulator could just be getting hot and glitching out on you after a while.

[bwatters60]

Thanks for the responses. My RT is titled as an '08, but the chasis is an '07 verified by the VIN. I've attached a picture of my isolator. I was able to verify the alternator is a CS-130D, and the when I had the alternator rebuilt the shop did replace a defective internal voltage regulator. Attached is an electrical system diagram from my RT manual (note that the copyright is dated 2006). It shows the relay in the lower left hand corner (the notations I added are italicized and underlined). With the ignition OFF or in ACC, there is no voltage on the IGN wire and the relay is open so no voltage is applied to isolator terminal E, the excitation terminal. With the ignition ON the relay should close and voltage from the engine battery should be applied to E. Since I don't get battery on the yellow wire with the ignition ON, there must be a break in the wire (fuses, at least the two possible ones I found, check good). If I manually apply 12V to the isolator E terminal, everything runs fine and the dashboard voltmeter registers about 14V. I also attached an diagram from Sure Power showing the electrical wiring of the isolator, alternator, etc. So, as I see it my choices are, 1) cap off the existing yellow wire and install a new line from and IGN fuse using a fuse tap, 2) trace the existing yellow wire through the harnesses to find the break and repair. And I may have to disassemble the engine fuse block. I hate to leave the hanging wire in Option 1, but in Option 2 opening the wiring harnesses looks to be a pain and disturbing the harnesses/fuse block has its risks. Booster, you're wiring diagrams may help me determine where this yellow IGN wire routes and/or terminates. Monday I may also give my Chevy service advisor a visit - he's a good mechanic (and a camper although towable) so he may be able to give me some good advice. If I'm missing anything, please let me know, and thanks again!

[booster]

I will try to dig out that section of wiring from the manual, I have used it before, but sometimes hard to find stuff in the poorly indexed manual.


The yellow wire to the ignition seems to be marked as an add-on wire, so not factory wiring. Unclear where it is tapped in though.


Be aware that the wires in the fuse box marked as "ignition" may be just that and used only to run the ignition. What you want to be hooked to with that yellow wire is the "run" and possible also "start" power section of the wiring. The fuses for those may be in the body fuse box instead of the engine one. The wiring diagram will tell, I think, but it is also possible there is an initiated signal from the computer that delays the start of the alternator until the rpm stabilizes, and I will look for that also.

[booster]

OK here we go, found the wiring diagram for the wiring of the stock charging system with an internal regulated alternator.


The wire colors are going to be very different than the Sure Power diagram you have as that looks like a generic one.





This is a purely internally regulated alternator setup, but it has a power control module computer controlled initiate, turn on, signal needed to operate. That signal wire is shown without any fusing so it is probably internally protected in the PCM and also very low power output. I don't know if that output would even be able to handle the coil of a mechanical relay. The fact that they want a 6 amp fuse in the line would indicate they may be using more power than it could supply.



If they are using the PCM output, you should be able to find the orange wire shown in the schematic and test it for the signal, which is likely delayed as I mentioned earlier after starting and won't come on without engine turning and stable.


The other wire in the schematic, as I understand it, is likely not the old sense wire would think of to run a gauge or reference the regulator to where you want it. It is marked as field duty cycle so the PCM would probably be using it to control fuel, timing, and rpm to adjust for load from the alternator.


You are back to trying to find where the yellow wire goes as it is highly likely an add-on and may be just connected with a line crimp in puncture splice connector which are used way too much.


My opinion, for what it is worth, would be to scrap the isolator and put in a separator/solid state charge relay which has a bunch of advantages.


Will charge both ways for both starting and coach batteries.


No voltage drop though it so coach batteries get full charge voltage.


Less wiring to deal with, no ignition connection.


Would allow you to go back to original alternator wiring.


You can even get them with a remote switch (more wiring though) to over ride them on or off or automatic, if you choose, which is a nice but more expensive way to go. We have had on for years that way and wouldn't be without it.

[bwatters60]

The yellow wire is definitely an add on, very likely by Roadtrek. I included the Sure Power diagram since it generally depicts how my RT is wired. The exception being Sure Power wired the E post directly to the IGN thru a 6A circuit breaker while RT used the IGN with a relay and a 10A circuit breaker to feed the E post.

I'm not sure how to interpret the wiring diagram you sent - it shows GY feeding C and OG feeding B. Is GY a green wire and a yellow wire? And OG an orange wire and a green wire? Or are these Green/Yellow and Orange/Green wires? And ports A and D are labeled not used. In any case, my generator has four wires into a four port connector - red, pink, brown and white (I assume this would be connected to A, B, C, and D on your diagram). And in both the Sure Power and RT diagrams, the sense wire (red in the case of RT) is connected to the engine battery (i.e., port 1 on the isolator) so electrically its the same as when it came from the factory.

No need to spend time responding about these wires, because you're right - I'm back to tracing the yellow wire. I'm going to talk to my service advisor Monday and get his opinion on where the yellow wire is likely terminated - in the engine fuse block, cabin fuse block, or somewhere else. Then I'm going to try and trace it down and find the break and remove the wire. I've ordered mini fuse taps and located a spare IGN port in the engine fuse block that provides 12V only when the IGN is on. So that is going to be the new feed for the exciter relay.

Appreciate the advice regarding the separator. "When" my isolator goes I will definitely research making this change. What separator did you go with, and did you convert from an isolator to the separator?

Thanks again for your feedback and the diagram!

[booster]

Just for my own curious mind, I have been looking for 4 wire pin out for that alternator and coming up empty, and no GM stuf with those colors. What I have found are some "pigtail" adapters that would be used to adapt the 4 wire plug that has two wires only used in it to another purpose and perhaps that is what you have on yours.



On older units with more connections, usually 3 wires, one of the extra would go to the brake warning system and another to voltage sense. The other two were the shown field % and initiate wires. Some even older ones had a battery wire like you see to the connector for turn on power, I assume, but that is now done internally from the main battery cable.



Our O7 is an after halfway through production year and it had a separator on it from Roadtrek, so can't compare to ours, unfortunately if it is a something special for the isolator. Perhaps someone else would know, that has that year with an isolator. You may want to follow the wire from the 4 wire plug back to see if the go to a main harness or splice into other stuff.


Very interesting, though, but no obvious information to be able to find.


We had a Surepower coil type separator in ours stock from Roadtrek. After one failure and tired of it using too much of or solar output, I replaced it with a Blue Sea bistable unit with remote switch. Almost no power use except when switching.

[markopolo]

I looked at the RT diagram for '04 and it has the relay so mine must have had it also. The '02 diagrams also have it so that's 5 model years & someone must have traced that yellow wire. Hopefully they'll see this topic.

Here's the Hehr Powerline test instructions and wiring diagrams I had saved from years ago: delco_hehr.PDF

One of the diagrams shows the use of a relay. The PDF should help you identify the wires by color and also shows the CS 130 to CS 130D conversion harness.

[booster]

Originally Posted by markopolo

I looked at the RT diagram for '04 and it has the relay so mine must have had it also. The '02 diagrams also have it so that's 5 model years & someone must have traced that yellow wire. Hopefully they'll see this topic.

Here's the Hehr Powerline test instructions and wiring diagrams I had saved from years ago: Attachment 8259

One of the diagrams shows the use of a relay. The PDF should help you identify the wires by color and also shows the CS 130 to CS 130D conversion harness.

That pretty much answered the question about the 4 different wire colors compared to the two factory wires. From the instructions one of the factory wires may be used but connected to the adapter.



As mentioned earlier, that yellow could be tapped into a fuse that doesn't say ignition and is just a "run" position one like most of the fuses are for the rest of the van stuff.


None of this changes the need to find that power source and why it is off, but nice to know why it looks so odd.


I wonder exactly when they changed to 244 style alternator like our 2007 came with as both the OP's and ours our 2007 model years. I also wonder if his has drive by wire, like ours, which also was in that year as a change.

[bwatters60]

I couldn't wait till Monday to talk to my service advisor, so yesterday I decided to trace the yellow wire (I call it ignition wire because its providing 12V to the isolator relay when the ignition is on) and learned that it was spliced into a light brown or light orange (hard to tell exact color) wire almost immediately after it entered the big harness (I should've know that Roadtrek would not have run the wire all the way down to the engine fuse block!). I didn't see it previously because it was on the far, or firewall side of the harness hidden behind the mass of wires within the harness. Turns out I had 12V at the splice and 0V at the relay. The yellow wire and blade connector was good, so the splice was bad/loose. So I removed the splice and taped up the ignition wire within the harness, and removed the yellow wire. Ran a new wire to engine fuse block and connected it to a fuse tap in #25 which was vacant and labeled Gasoline Spare (only provides 12V with ignition on - installed a 10A fuse since relay draws only 133mA). Problem solved. I wish I would've found that splice on my first peek into the harness and I would've saved booster and markopolo some time. Marko that's an excellent Powerline doc you supplied. Thanks guys for your suggestions and docs!

[Gastineaurower]

I had a 2008 Adventurous that had no juice to the ignition switch despite ample charge in the engine battery. The problem baffled the Mercedes Mechanics, who returned the vehicle to me several times only to have the problem recur. They told me that Roadtrek had somehow screwed up the wiring. When I finally got it to Poulsbo RV (after $1500 in wasted repair bills to Mercedes) they immediately recognized that the problem was in dead or dying house batteries. Seems that the signal that tells the electronic ignition switch the there is power to crank the engine is routed through the house battery system. You may have a very different problem — different vehicles, different engine — but just for the hell of it, check your house batteries.

[peteco]

Originally Posted by bwatters60

The yellow wire and blade connector was good, so the splice was bad.

I had a bad Roadtrek installed clip-on splice on the rear upper clearance lights on my 2006 RT 210P. Had to remove the kitchen wall to get to the splice.

So the general lesson is to check/verify splices early in the diagnosis process before changing components.