Lost knowledge


Back in the day....

Golden Jubilee
Golden Jubilee

Posts: 2852

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Mon Feb 13, 2017 10:20 pm

Re: Lost knowledge

Well, it is a fallacy that the "computer" will tell you what is wrong. Ask Smogguy, It will point you to the circuit that is out of wack, but it still takes someone who understands the system to find the problem.
I was working on a Neoplan coach. It had DDEC and an Allison that interfaced with it. Neoplan didn't see fit to wire up the diagnostic light. I read the book, found the wire and pulled the codes and called Neoplan (they were under warrantee) to ask what they were going to do about fixing it. They asked how I got the codes as they didn't provide a hook-up to retrieve them. Why they built the bus without a connector or light to pull codes from I'll never know.

Golden Jubilee
Golden Jubilee

Posts: 5691

Joined: Thu Dec 27, 2012 12:45 pm

Location: Canada's left Coast

Post Mon Feb 13, 2017 11:22 pm

Re: Lost knowledge

Maybe the company purchasing agent ordered the coach without a diagnostic port.
There were two diagnostic ports on the vehicles I am familiar with. One was around the driver's area and the second was in the engine compartment. There was a third connection in the sealed compartment where the computers are and an interface, transmission to engine, if required.
The DDEC I was familiar with contained a terrific amount of information. It was possible to download fuel consumption details against time periods, acceleration and deceleration, what gear or gears were used at the time of an event, engine over-speed, brake application, engine and transmission temperatures brake application intensity along with the expected engine and transmission diagnostics. There was one event where a driver claimed a slower speed than the amount of collision damage would indicate. The driver also claimed he had applied the brakes and they did not respond. The DDEC download showed the vehicle was travelling at 44kmh in third gear and the road speed went to zero in .250 of a second. The DDEC also showed that the driver had full throttle request at the time of rapid deceleration and the brakes were not applied.
DDEC always fascinated me. The systems were trouble free, mostly, with some lasting decades. It was almost always the wire connections that failed the pre- Weather Pack days, from water ingress. http://www.weatherpack.com/ Weather Pack was the best thing to enter the industry.
I would rather have tools I do not need than to need tools I do not have
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