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Amber & Red check engine lights?? And over ride
I’ve luckily never had the experience where either one of the check lights have come on so what is the protocol on what happens when either light comes on, And what is the over ride switch for?? And when do you push it??
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9 Replies
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The amber check engine light (CEL) is to let you know something needs attention. The list of things that will trigger a CEL is extensive but generally speaking it is a condition that will not prevent continued driving. Depending on the DDEC level it can include emissions issues and some conditions may cause the engine power to be derated.
A red stop engine light (SEL) on most coaches is a signal the engine shut down is imminent. On most older coaches only low oil pressure, low coolant level and high engine temperature will shut you down. On later model coaches high oil temperature will also shut you down. If you get an SEL the over ride switch will provide you with a short time period to prevent shutdown. If for example you are in the fast lane and need to get to the shoulder it is appropriate to use that over ride.
It is not uncommon for a CEL or SEL to occur with no other problem than a faulty sensor or perhaps a bad ground. I have had real problems that the SEL or CEL alerted me to such as a failed radiator hose creating low coolant level giving me a SEL, or a lazy #1 injector giving me a CEL. Neither showed in my dash gauges, but they were real issues that needed attention.
I trust but verify because with every bus I have picked up a reader from ebay and when I got the CEL or SEL I could plug in my reader and see exactly what specific problem was creating the light. I have learned to always trust the lights, but to dig a little deeper to determine the problem and to help define my response. On most coaches you can use the information center or pro driver to get a little detail if no reader is available. Early DDEC coaches have provisions for flashing the codes.
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Jon, is there a particular reader that you (possibly on Amazon?) would recommend for a Classic vs. the more electronically complex Elegant Lady model Liberty coach?
Jeff and Lindsay
91 Marathon XL -
The readers I find are Nexiq, found on ebay and I try to find one that has the card or cartridge for my appropriate DDEC version. I have paid as low as $500 and as high as $1000. My current reader has DDEC V software, but also has software to diagnose my ABS and my transmission so that one was a lucky find.
Readers can be a hand held dedicated reader or software to allow the use of a laptop. My preference is the hand held reader because I can drive with it plugged in and with it next to me read faults or other data easily. The cord is long enough it will reach the passenger seat where my wife can read data for me.
The converter or model of conversion doesn’t matter because this is a chassis reader. Prevost has plugs for the reader under the dash near the key, or under the rear electrical box in the engine area.
I like the reader, not only because it does a good job of defining a fault, but it can be used to read almost any value needed from the engine. I can read temps, pressures, voltages and any other information and get information I need to determine how every thing is doing or to compare to the dash gauges.
The values the reader shows are the same values DDEC is using to detect faults. There are aftermarket devices that can display DDEC information also which gives you a lot of options on how to get detail needed to evaluate your engine.
These are just examples. The second link shows ABS as well as DDEC III and DDEC IV.
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As always…a thorough write up with practical applications/explanation of use and why! Your knowledge and willingness to always share is truly Priceless!!!
You help us rookies feel like we just might be able to operate these beautiful Goliaths and keep them on the road for many more years!
Really like the idea of this Reader (w/ABS codes, too)…not that I’m mechanically qualified – but, that it will allow the ability to talk intelligently with skilled mechanics; know what the potential/actual problem might be – and, therefore, be less likely to be “played” by any unsavory shop. Yet another aspect of Safety on the Road.
Thank you always, Jon!
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I have a scan gauge on dash I wonder if it will read codes? And Jon the over ride switch is it a momentary switch, hold it in and start engine and move bus?? Thanks’ Jon for info.
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If it weren’t for the outrageous dues money Jon wouldn’t be able to offer such technical expertise, you would have been told “Just take it to Prevost”
Do the math, with over 5000 members paying dues he can afford one or two.
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Art, the over ride is momentary. In your operator’s or owner’s manual (on line if you need one) it should tell how many seconds you get each time you press it.
When I had a ruptured radiator hose I had to hit my over ride 2 or 3 times because I was on I-40 near Nashville and it got me to the shoulder during heavy traffic.
Maybe someone can tell us how much additional time it gives us?
Buddy, you need to quit reminding me of how painful it is to see Tom spending my share of the dues money, and instead put pressure on him to start sending it my way.
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I’m answering my own question about the scan gauge, It says it will read codes, I use it for oil Psi engine temp lots of accurate info and I guess it will read codes.
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I bought 2 Kent Moore J-38500 Pro Link Scan tools and a Kent Moore J-37164-DDEC Sensor Tester and at Auction a while back. Neither has the cartridge’s. Same as the Pro Link Scan tools. The Sensor Tester is intact with all wiring.If somebody need to borrow one, holler.
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