Check Engine light - MCI 102C3

JT4SC · March 19, 2017, 09:11:27 PM

Hello everyone,

I'm excited to take my kids on their first long road trip in the Moose! We are going from San Diego to the Grand Canyon for a week. This is also our first trip towing a car behind the bus. We are towing my wife's minivan on a tow dolly. We made it to my in-laws tonight approx 100 miles away but not before the check engine light came on. It first came on shortly after we left. Everything in the engine compartment looked and sounded normal, so I turned the bus off as well as 24 volt bus electricity. When I turned both back on the check engine light was off and all was well. Unfortunately the check engine light came back on approx 5 miles later as we pulled on the freeway. I decided since everything looked and sounded good I would keep going. The bus ran great, everything sounded and looked exactly like it's supposed to. All the gauges were normal.
Any ideas what this could be? My guess is it could have to do with towing the car, maybe the extra weight tripping a sensor or something? I installed a back-up camera yesterday but only spliced into the license plate lamp for power.
Any help would be appreciated, thanks!!
Jimmy

buswarrior · March 19, 2017, 10:51:32 PM

One answer:

Put the scan tool on it and find out.

Get yourself one for your coach, this won't be the last time...

Full stop.

Otherwise, your question will produce as much clarity as asking: What flavour of ice cream do y'all think I should buy the kids?

When you have the codes, THEN turn the busnuts loose on that info!

happy coaching!
buswarrior

luvrbus · March 20, 2017, 05:24:32 AM

What engine in the 102C3,Cummins,Cat or Detroit and the check engine light is not always a engine code problem

JT4SC · March 20, 2017, 06:37:57 AM

Quote from: luvrbus on March 20, 2017, 05:24:32 AM
What engine in the 102C3,Cummins,Cat or Detroit and the check engine light is not always a engine code problem

Detroit - 6v92 DDEC

JT4SC · March 20, 2017, 06:38:43 AM

Quote from: buswarrior on March 19, 2017, 10:51:32 PM
One answer:

Put the scan tool on it and find out.

Get yourself one for your coach, this won't be the last time...

Full stop.

Otherwise, your question will produce as much clarity as asking: What flavour of ice cream do y'all think I should buy the kids?

When you have the codes, THEN turn the busnuts loose on that info!

happy coaching!
buswarrior

I will 100% go and buy this tool, thank you!!

luvrbus · March 20, 2017, 06:44:48 AM

You can flash the codes without a Pro/Link you just cannot clear some codes ,you have any idea what version of DDEC you have,buying a scanner Pro/Link you need the right software or you wasted your money

JT4SC · March 20, 2017, 07:02:19 AM

Quote from: luvrbus on March 20, 2017, 06:44:48 AM
You can flash the codes without a Pro/Link you just cannot clear some codes ,you have any idea what version of DDEC you have,buying a scanner Pro/Link you need the right software or you wasted your money

I don't know. It's a 1993 bus which was the last year they made the 102C3's. Im going to do some research.

luvrbus · March 20, 2017, 07:05:59 AM

That one could be a ll or a 111 that was the change over years

JT4SC · March 20, 2017, 07:16:10 AM

Quote from: luvrbus on March 20, 2017, 07:05:59 AM
That one could be a ll or a 111 that was the change over years

I'm 95% positive it's a ll, trying to confirm.

scott332 · March 20, 2017, 07:25:07 AM

On my bus (1992 MCI MC-12 DDEC III) I can turn the master switch ON (with motor NOT RUNNING), then flip the ENGINE OVERRIDE switch 3 times. This will flash the engine codes, there are 2 lights on the dash that will flash, you count the flashes between the short pauses to get the numbers. FLASH FLASH FLASH short pause FLASH FLASH long pause. This example would be code 32. All of the codes in the computer will flash like this over and over until I flip the ENGINE OVERRIDE switch one more time to make it stop.

JT4SC · March 20, 2017, 07:50:55 AM

Quote from: scott332 on March 20, 2017, 07:25:07 AM
On my bus (1992 MCI MC-12 DDEC III) I can turn the master switch ON (with motor NOT RUNNING), then flip the ENGINE OVERRIDE switch 3 times. This will flash the engine codes, there are 2 lights on the dash that will flash, you count the flashes between the short pauses to get the numbers. FLASH FLASH FLASH short pause FLASH FLASH long pause. This example would be code 32. All of the codes in the computer will flash like this over and over until I flip the ENGINE OVERRIDE switch one more time to make it stop.

I tried this but I don't have a switch just a "Emergency Engine Overide" button. I flipped the master switch, did not turn the bus on, pushed the override button 3 times but nothing came up.

I started the bus again and the check engine light is back Off. I would assume it will turn back on again after a few miles of running. Obviously in a car the check engine light will come back on everytime, even if you cycle the battery. Is this how it's also supposed to work on a bus?

thomasinnv · March 20, 2017, 07:58:01 AM

Not sure about the C but on my D model there is a button and a check engine light in the A/C junction box in the front luggage bay.

Sent from my SM-G920T using Tapatalk

JT4SC · March 20, 2017, 08:30:27 AM

Quote from: thomasinnv on March 20, 2017, 07:58:01 AM
Not sure about the C but on my D model there is a button and a check engine light in the A/C junction box in the front luggage bay.

Sent from my SM-G920T using Tapatalk

I looked in the front luggage bay but did not see any junction boxes.

JT4SC · March 20, 2017, 02:15:01 PM

Update - everything continued to run fine, took it to gas station, filled it up and now won't start. I believe it's a battery issue, which doesn't make a lot of sense since I keep a trickle charge on it when not in use, plus it started like normal 20 mins before it wouldn't start again. Man bussing is a love/hate relationship!!

eagle19952 · March 20, 2017, 03:11:32 PM

Quote from: JT4SC on March 20, 2017, 02:15:01 PM
Update - everything continued to run fine, took it to gas station, filled it up and now won't start. I believe it's a battery issue, which doesn't make a lot of sense since I keep a trickle charge on it when not in use, plus it started like normal 20 mins before it wouldn't start again. Man bussing is a love/hate relationship!!

The most common reason for a check engine light is low coolant...check that.