Voltage problem

[Daniel McShane]

Drive west on I 40 and voltage on chassis and coach batteries started fluctuating from 12 - 14 volts. Put meter on batteries and showing 15v, not good. I still have the echo charger which is under the bed in the engine compartment, I am assuming that it has failed. Any suggestions. Luckily there is a koa where I exited I 40.

[Daniel McShane]

Could this be my aternator and is my understanding correct that the echo charger charges no matter the power supply, cat, shore or genny.

[Jerry Emert]

As far as the fluctuating gauge goes, that happened to me a couple years ago.  I found a loose wire on the back of the alternator. Tightened it and no problems since. So that is probably a ground issue somewhere.    As far as 15 volts with engine running, that seems higher than normal 14.2 VDC.  I'm not an expert but 15VDC probably won't hurt anything in the short term but may indicate a regulator problem developing.  I think you are correct about the echo charger.  Good luck.
Jerry

[Daniel McShane]

Thanks for the input Jerry. Just hooked up to shore power at the KOA and voltage went high again, got a reading of 14v and steadily increased to 15 and climbing when i unplugged, am i correct in thinking its the echo? Also high on genny power. Now where to get a rerplacement in the middle of oklahoma?

[Daniel McShane]

Isn't the echo charger the voltage regulator??

[Steve Huber Co-Admin]

Daniel,
The echo charger is a  voltage follower, not a true regulator. It does limit the output voltage to 14.4 if the input reaches that level.
When on shore power, you may see high (15+ volts) at the battery from the solar panel circuit. There is almost no currect though. Try covering the panel(s) to verify.
Jerry's comment re a loose connection is very possible. I had one in my rear electrical bay that caused voltage to fluctuate between 12 and 13.7v when driving both on alternator and generator.
Steve

[Gerald Farris]

Daniel,
Your problem is not your Echo Charger. The Echo Charger simply passes charging voltage from the house batteries to the chassis batteries only when the house batteries are being charged. It can not increase the voltage above the charging source voltage. The charging voltage for the house batteries is regulated by their charging source, either the engine alternator or the inverter.

From your description, it sounds like you had the generator running while driving and the inverter is overcharging your house batteries. If the generator was not running while you were driving, you have two charging sources that are overvoltage that probably means a connection problem. To solve the issue, you need to run a through circuit test of your charging systems, both the inverter and engine alternator. This test should be ran with the solar panels covered so that the 5 or 6 amps from the solar panels does not confuse the results.   

Gerald

[Daniel McShane]

Gerald, I did find a severely corroded wire, 16-14 gauge, on the positive terminal of the chassis batteries (sense wire?). I removed the wire, replaced the connector and reconnected. Went to start and cat wont go into its normal sequence, no wait to start for warm up and what ever else it does. Checked every fuse I could find, Allison included. Not sure what else to try.

[Gerald Farris]

Daniel,
The wire that you worked on may be the one to your ECM (engine control module). Double check that it has a good connection to the battery. I am not sure where the ECM fuse is located on a 1999 Monterey, but on most SMC built coaches it is in the upper part of the battery compartment.

Normally if you work on something and something else stops working, it is caused by something that you did wrong. Double check everything that you did, and if it checks out OK, check the power circuit for your ECM.

Gerald   

[Daniel McShane]

Gerald,
I agree, I have caused colateral damage over the years working on various things be it home or auto. The wire I replaced the terminal connector on was RED as is the one at the alternator, not sure which wire goes to the ECM.  I called a mobil tech and after a couple hours he says he's sure the ECM is bad.  He said he wasn't receiving the proper signals from the data link in the service compartment, nothing from the ECM.  My production year is 98 so thats 20 years and from what I understand these ECM's do fail. I'm 65 miles west of OKC and will have to get a tow on Monday back to OKC, the tech suggested Premier Freightliner over a local Cat dealer due to Cat's high hourly rate.

[Daniel McShane]

So with power TO the ECM and no signal from the ECM would it be safe to assume that the unit has indeed failed. I've crawled all around and can't see anything obvious. It sure is a coincidence, perhaps my voltage spikes took it's toll on the ECM but not bad enough to blow a fuse. Thank you to all that contribute to this forum, I've spent countless hours reading all I can about my coach to educate myself as much as possible. It's comforting to have the Beaver Ambassador Club on the road with me, again, many thanks.

[Steve Huber Co-Admin]

Daniel,
If you've got 12v at the ECM then the fuse is OK. Since the outputs are data lines and thus not fused, it would seem the ECM is faulty, unless there is a bad connector between the ECM output and the data jack.
Steve

[Gerald Farris]

Daniel,
I personally would feel better about a diagnoses of a bad ECM from a Cat dealer than from a mobile tech or a Freightliner dealer because a Cat ECM can be expensive. However, if it is a large Freightliner dealer that has been around a long time, their techs should be proficient with Caterpillar ECM diagnostic procedures since Freightliner used to use a lot of Cat engines. Caterpillar has not built a diesel engine for highway use in over 8 years, so the expertise that is necessary to properly a Cat ECM failure is not at every truck shop.

Gerald       

[Daniel McShane]

The journey continues.....Oklahoma City Caterpillar no longer works on motorhomes (coaches).

[Daniel McShane]

Same with Rush Truck Center.