check engine light

September 11, 2015, 01:08:15 pm

There is a light for check engine. I am assuming that if there is a check engine light, the there is a receptacle that one can plug a "reader" in to find what the problem(s) is/are. Can anyone tell me where this receptacle is and the unit I many purchase or get to read the codes for diagnostic purposes. My home is a 1989 Grandvilla Unihome Detroit and Allison. Thanks.

Re: check engine light

Reply #1 – September 11, 2015, 06:11:50 pm

Curtis,
Two Detroits were used in that era: 6V92 and a V8 8.2 liter. Maybe only the 6V92's were used on GV's - I'm not sure.

I can't help you on the 8.2 liter (I think it's all mechanical so no check engine light) but if it's a 6V92 here's the info:
There should be a dash light for the Check Engine. It should go on for a few seconds when you first turn the ignition on. If not the light might be burned out. An Engine Shutdown light should also illuminate during ignition power up too.

The diagnostic plug should be mounted under the dash - above where your left toe would be. Here's a post about it with a picture: 2nd Diagnostic plug DD 6v92

ProLink is the professional reader. Search the forum for "Prolink" - many posts about it.
VMS (Silverleaf), pcVMS are "readers only" and usually permanently mounted on the dash to give you info while driving. A lot of post on this as well.

You can read the fault codes without a reader too. There should be two switches under the lift-up dash top. One is for the engine and the other is for the transmission. With the switch ON, you turn the ignition ON (engine not running) and "read" the fault codes by the blinking of the Check Engine light on the dash. It's a two digit code with long and short pauses between blinks. It will repeat out the codes indefinitely as long as the ignition is on. Your owners manual has details on how to do this and what the codes mean. The codes are universal to Detroit Diesel (not Foretravel specific) for the DDEC II so code cheat sheets are readily available on line.

Re: check engine light

Reply #2 – September 11, 2015, 06:52:14 pm

John spells it out nicely. All Foretravels with 2 cycle Detroits use the DDEC II otherwise known as Detroit Diesel Electronic Controls. The cartridge slides onto the backside of the reader. Cartridges are available for almost all electronic HD diesels, brakes, Ford, GM, etc, etc. The cartridge you want is either the DDEC I & II or the DDEC II & III. The readers were made for several companies so will have MPSI, Detroit, Kent-Moore, Nexiq or possibly another name on the face. I have a couple of sets (don't want to sell) and bought them off ebay for well under $200.

Searching for one that would work took me a while using all the names above. Lots of operational info online or I can email PDFs if the manual does not come with the reader/cartridge.

Below is a photo of one of mine as an example with the codes in another attachment.

It will do lots of stuff but will not reprogram the ECU for more power.

Pierce

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