‘94 U300 Unihome Engine Diagnostic Port

Topic: ‘94 U300 Unihome Engine Diagnostic Port (Read 953 times) previous topic - next topic

‘94 U300 Unihome Engine Diagnostic Port

August 31, 2020, 05:52:44 pm

I'm trying to locate the DDEC engine diagnostic port in my coach, but have only located the Allison Transmission port.

There are some cut wires underneath the dash, but I don't know if they are related (see pics).

Any ideas are appreciated!

Thanks!
Chip

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #1 – August 31, 2020, 06:06:46 pm

Not sure if this is helpful but on my '93 U300, that is the area where I found the port. It had a cover on it.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #2 – August 31, 2020, 06:08:51 pm

The cut wires are not cut. They are spares that go to backbof coach. Your data plug is in second picture. Lift dash up and in front of steering wheel area you should see 2 switches. One us for transmission diagnostic the other is engine.
You select which one you want to read

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #3 – August 31, 2020, 06:19:23 pm

Ah! I was expecting to find another round connector and thought it was only for the transmission!

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #4 – August 31, 2020, 06:26:39 pm

I have a Bluefire data adapter and think I need to get an adapter cable here:

http://obd2allinone.com/products/ALDLto6Madap.asp

Then it sounds as if I need to flip the engine switch Stump indicated to make the ddec data live on the port.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #5 – August 31, 2020, 07:29:59 pm

When I hook up my prolink to that port I do not hit that switch, that port goes right to the ECU.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #6 – August 31, 2020, 07:38:59 pm

Same as Andy.

P

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #7 – August 31, 2020, 08:32:56 pm

Thanks all! This community is fantastic!

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #8 – August 31, 2020, 09:02:40 pm

Andy, Chip: I have a thread running on the 6V92 and the Bluefire. I mentioned I was getting engine data and chassis data ( battery etc. ) but as the thread states very little transmission data ( as in none except torque lock intermittently). Wonder if I flip that switch I will get tranny info? If so wonder if they can be combined. Can't get to the coach until Wednesday. Any chance I can get a picture of the switch and location?

Chip: Look for my thread, just posted a couple of days ago. Have a rundown of the data coming out and am trying to set up a dashboard as we speak. Yes you need an adapter. Model and where to get it is posted. Works perfectly. Want to get tranny info so anxious to try it next time over to the coach.

I truly love this forum. NOTHING can replace experience.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #9 – August 31, 2020, 09:08:50 pm

Chip: Here is the adapter you need. Worked perfectly. Attachment below.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #10 – August 31, 2020, 09:21:22 pm

Chip: Search for Bluefire Monitor for 6V92 Detroit. in Tech Talk forum ( this one ), 3 days ago. Maybe we can do this together and save us both some grief.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #11 – August 31, 2020, 10:34:00 pm

Sounds good Steve - I have an adapter cable on the way now. I forgot to check your other posting for updates. Looks promising!

I was not really sure what to expect data-wise, and it looks as if there are a number of parameters to work with. Hopefully we can figure out the transmission monitoring too.

I'm a little confused about the switches Stump helped with. Why would there be an engine and trans switch if the engine is passed through by default?

If both engine and trans connect via serial communications, there won't be a way to monitor both simultaneously from the same port. Unless a splitter and two independent connections could be used...

Maybe it's a different kind of comms standard?

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #12 – September 01, 2020, 12:56:39 am

Chip: Thats what I'm thinking. Believe it might be an " either/or" proposition. Almost sure I know the switch but looking to confirm. Combining the signals would be tough and frankly not sure I would. If the systems were created to be independent at the factory they must ( hopefully) have had a reason. Not sure I want to create some kind of feedback path. We don't have that much electronic stuff in our vintage rigs but I'm a cautious guy.
Will be at the rig Wednesday. Will let you know how it goes.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #13 – September 01, 2020, 09:38:16 am

Steve/ Chip here's a couple of pictures from under my dash lid, not sure if it will help. I think those switch's will flash a lite from under the dash and the number of blinks is supposed to mean something not sure what?

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #14 – September 01, 2020, 04:51:41 pm

I found a DDEC-II diagnostic codes card.

I turned the ignition on, flipped the engine button under the dash in Andy's photo, and the CEL started flashing. So that's what the switches are for - manually reading codes by translating CEL flashes.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #15 – September 01, 2020, 06:53:24 pm

If your patient, you can read any active or stored codes for the engine and transmission. Best is to have both the Bluefire instrument panel on a tablet and a Pro-Link 9000 tool so you can read all the other stuff, test injectors, fast idle (Detroits should not 600 rpm idle for extended periods) at 1000 rpm. Cheap investment if you go to the shop to have the data read even one time. All Foretravel 2-cycles are DDEC II.

Pierce

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #16 – September 01, 2020, 07:24:00 pm

What codes did you get?

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #17 – September 03, 2020, 05:06:30 pm

I got the following engine codes:

22 - Throttle Position Sensor Low Voltage. I think the was due to me turning ignition on without the throttle pedal connected - was replacing flooring. It generated a check engine light at time. I did not crank the motor, though I doubt it would have cranked anyway. Am I on the right track here, or is this sensor on the motor?

35 - Oil Pressure Sensor High Voltage
43 - Low Coolant Level
44 - Engine Overtemperature
46 - Low Battery Voltage

I've carefully monitored engine temperature in the few hours I've had the coach on the road - are these codes stored and haven't been cleared from an earlier event? Like my guess on the throttle position sensor?

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #18 – September 03, 2020, 06:53:25 pm

More than likely from a previous event. You need to clear them and see if they come back.

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #19 – September 03, 2020, 08:40:59 pm

Is there a way to clear them without a Prolink 9000? I have my eye on one but haven't pulled the trigger yet.

Thanks!

Re: ‘94 U300 Unihome Engine Diagnostic Port

Reply #20 – September 03, 2020, 09:30:03 pm

Quote from: Chip7 – September 03, 2020, 08:40:59 pm

Is there a way to clear them without a Prolink 9000? I have my eye on one but haven't pulled the trigger yet.

Thanks!

No either prolink or DDDL software. Call your local freightliner place tell the service mgr you have a coach you bought. It has DDECII ECM.
Tell them you bought the coach and fault codes were stored and you want to start off fresh and see if any come back. Ask if they would just clear them for you. If you are in Charlotte nc area I'll do it for you

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