BAC Forum

General Boards => Technical Support => Topic started by: Mike Shumack on November 17, 2018, 04:03:06 PM

Title: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Mike Shumack on November 17, 2018, 04:03:06 PM: I'm doing a few repairs/tasks on the Coach this week and came up with two questions.

Previously my Cruise Control was not working. Pressing the Set or Resume (cruise control) button did not raise speed and in Aladdin the Cruise Control always showed OFF.
So I started troubleshooting with the SmartWheel manual. I found a loose connection on the J1 connector. With that repaired, I can now raise engine idle speed with the Set or Resume buttons.

Question 1: On the Aladdin display > Engine/Trans Status shows "Cruise Off". However since I can raise the idle now, the Cruise must be on. Is it normal for cruise to show OFF when the coach is not moving or should it show On whenever the steering wheel button is pressed On? Maybe I have more troubleshooting to do.

Question 2: With the engine off, and coach plugged into shore power (20A) i am hearing a (pretty loud) high-pitched humming coming from the Big Boy solenoid. Is this normal?

Thanks.
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Lee Welbanks on November 17, 2018, 09:13:15 PM: Mike, I'm going to fire up the PT later to day or in the morning so I'll see what mine reads on or off.
My Big Boy hardly makes any noise at all, you can hear a faint hum but not much. Have you rebuilt that relay? The contacts may be corroded causing them the chatter.
I'll let you know what my aladdin shows.
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Jerry Carr on November 17, 2018, 09:56:18 PM: on our 06 PT we did often hear a hum
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Lee Welbanks on November 18, 2018, 06:03:59 PM: Mike,
Fired up the coach this morning and with the rpm's set up on the cruise the Aladdin reads cruise off.
My big boy hums just a little, 10 ft away you cannot hear it.
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Mike Shumack on November 18, 2018, 06:10:11 PM: Thanks Lee. It sounds like my equipment is functioning normally.
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Scott Shearer on November 18, 2018, 07:07:17 PM: 2006 Thunder

Our Aladdin display will show cruise speed 0.0 and “Cruise Off” until after the cruise control is initially engaged (at hi-way speed), it will then indicate the cruise speed setting and “Cruise On” (even if the cruise is disengaged).

Our Big Boy also hums, always has, even after rebuilding.
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Stan Simpson on November 18, 2018, 07:23:51 PM: Quote from: Scott Shearer on November 18, 2018, 07:07:17 PM
2006 Thunder
Our Big Boy also hums, always has, even after rebuilding.

Our Big Boy has never hummed, apparently it knows the words. ::)
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Lee Welbanks on November 18, 2018, 10:17:22 PM: Quote from: Mike Shumack on November 18, 2018, 06:10:11 PM
Thanks Lee. It sounds like my equipment is functioning normally.

Mike, Its anybody's guess what is normal operation with these coaches. I don't think there are two built the same to many moving parts.
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Mike Shumack on November 19, 2018, 05:12:13 PM: I got a call back to my question submitted to Intellitec. M&M RV Electronics called me - they said the hum is normal. It's from the pulsing of the hold-in coil.

He also said to check the voltage drop across the main terminal lugs. If the drop is over 0.1V then the Big Boy is bad.
Title: Re: Is Big Boy relay supposed to hum? Question on Cruise Control
Post by: Bill Lampkin on November 19, 2018, 05:40:19 PM: Mike, Might be worth it to just take the Big Boy out and clean the contacts inside. Simple solenoid, just like on a starter motor. Nice article and photos on the headlight replacement!