Transmission Codes on MD 3060. Monitor reads 5

[dbarton291]

Originally Posted by Andy M

No, take a look at my pic, the connectors are identical in color and shape, as they are both black.

Ah, got it. Thank you. I'll take a look tomorrow and see if I can verify you are probing the correct connector.

[Andy M]

Also take a look here. It shows a yellow and white wire for 27 and 28 pin location at the ecu harness. Mine are white and red wires. I am a little confused at this as well, although my coach is a 1997 Monaco and this revision guide is a 1998 revision guide.

P.S. I would think that red would be appropriate to represent power and white can be appropriate for ground.

http://www.wanderlodgegurus.com/data...ualMD_HD_B.pdf

[Andy M]

The lockup clutch being disabled is probably why the temperature climbs.

Understood.

[Andy M]

The one thing that is sticking in my mind about this one is what if the C3 switch is intermittent or sticky?

Regardless, I have a no continuity when the harness wires 27 to W and 28 to X are probed . The 27 and 28 is open when ohmed. The ohm meter does nothing. There is a break somewhere in the harness on both wires. This is why I made mention, how many more wires could be broken, and yet the trans still function?

If I had continuity, the ohm meter would read 0.01 to 0.03, as it does when I test a piece of 50 foot 18 gage wire.


It's not a question of "if" it's a question of "when" I find the break, and hopefully I will find that problem area in the harness tomorrow.

[dbarton291]

Here is what I am showing in my troubleshooting book.
The connectors at the ECU are labeled (B)black and (A) black/white. The A connector must have a white stripe on it somewhere. The connector that has the C3 pressure switch circuit is the B Black connector.
The C3 pressure switch power is circuit 162. The Allison color recommendation is White.
162 runs from ECU B28 to Transmission feed through X.
The signal ground is circuit 161. The Allison color recommendation is yellow. It runs from ECU B27 to Transmission feed through W. My book is a 2005 revision but it matches the one you referenced.
Keep in mind the chassis harness may not have been supplied by Allison. Some OEMs sourced their own. Today, Allison does not provide any chassis harnesses. In an OEM harness, the colors may not match, but the circuit numbers should. Look for the circuit number printed on the wire.

[dbarton291]

Originally Posted by Andy M

Regardless, I have a no continuity when the harness wires 27 to W and 28 to X are probed . The 27 and 28 is open when ohmed. The ohm meter does nothing. There is a break somewhere in the harness on both wires. This is why I made mention, how many more wires could be broken, and yet the trans still function?

If I had continuity, the ohm meter would read 0.01 to 0.03, as it does when I test a piece of 50 foot 18 gage wire.


It's not a question of "if" it's a question of "when" I find the break, and hopefully I will find that problem area in the harness tomorrow.

If those wires were open, you would be getting codes 32 XX. This code indicates the C3 pressure switch is open when it should not be.
You are getting codes 57 XX indicating the circuit is closed when it should not be.
Your continuity check on those circuits does not make sense. You jumpered the two together on one end, checked at the other and got 7 ohms. That indicates there is continuity but it's a little higher than spec. 7 ohms under those circumstances is not unheard of.

Then you checked the wires individually and got open circuits. You can't have continuity when looping open circuits. I would redo that test.
Also check for shorts between wires. Put one meter lead on X and touch all other wires. Put one meter lead on W and touch all other wires. Check any continuity readings against the schematic.
You can also check the harness for short to ground. Disconnect both ends of the harness. Touch one meter lead to X and then touch the chassis. Touch one meter lead to W and then touch the chassis. This will reveal if the harness is chafed against the body anywhere.

[dbarton291]

Originally Posted by Andy M

Also take a look here. It shows a yellow and white wire for 27 and 28 pin location at the ecu harness. Mine are white and red wires. I am a little confused at this as well, although my coach is a 1997 Monaco and this revision guide is a 1998 revision guide.

P.S. I would think that red would be appropriate to represent power and white can be appropriate for ground.

http://www.wanderlodgegurus.com/data...ualMD_HD_B.pdf

According to the book Red is already taken in that harness. It is battery power. Black is used as battery ground.
Don't worry too much about the color codes. It may not be an Allison harness. Go by the circuit numbers on the wires. If there are not circuit numbers on the wires, the harness was not made to the Allison spec. and you'll have to rely on the connector cavity labels.

[Andy M]

dbarton, I appreciate your willingness to help and confirm, thank you. The past 2 to 3 days have been borderline overwhelming, but I am one that will take a breather when needed, so that I can regroup and go at it again with a clear head. With that said, I was led down the wrong path, as I was trouble shooting the incorrect connector, of which had me baffled and thinking that my wiring for some reason does not pertain to the wiring diagrams, of which had revisions for time to time. To confirm, the back of the connectors are white and black. I was trouble shooting the white, when I should have been trouble shooting the black, and in the process by doing so, had me coming up with broken wires somewhere from the front to the back harness. You go based upon the knowledge that is fed to you, and I apparently had a tech instruct me of the wrong connector. Frustrating to say the least, and I did not spot it in the diagrams, or maybe I missed it, that the connector needing to probed, should be the black backed connector, as they both have the same numbers on them, making for the additional confusion. So, after ohming and probing two days worth of circuitry, the Allison tech asked for pictures of the connector, and after I sent him front and back pictures, he still never made mention that I was in the wrong connector, and said "hey, why don't we try the other connector, and as quick as I moved to the other connector, and found and probed pin 28 and 27, and checked for continuity at the back, bingo I have a good wiring harness and the issue is not the harness. Between myself and the tech in Phoenix, who I've been working with on the phone, we have come to the conclusion that there is a hell of a good chance that my issue is in the C3 pressure switch. Now, to this point I have taken time away from my race engine shop and need to get back, as I have an abundance of work to take care of. This afternoon I decided to head down to the local Allison service center to speak with the lead techs and service manager, and as we huddled together, I gave my explanation of the issue and what I have done, and after that explanation, we are all on the same page. C3 pressure switch, and since it is 21 years old, we need to change out the internal harness as well.
I can do this all myself, but my business will suffer, so with that said, I will be at Allison in the morning, as they said "not a problem Andy, bring it in first thing tomorrow and we will get that valve body down, change the C3 pressure switch, harness and get you back rolling again. There was some slight talk, that there is a small possibility that it could be the ECU, and I would have to agree, you just can't rule anything out. I am keeping my fingers crossed that we mailed the problem, and that it will be behind me from tomorrow on.

I will keep you posted on the outcome, as I plan to test drive it 5 or 6 hours this weekend.

[dix39]

Not to distract from the problem at hand, but having just bought a '94 Dynasty with the MD 3060, I wondered where I might find manuals and other information about the beast? From records that are with the MH, the PO recently spent in excess of 7k having Freightliner of AZ chase and repair transmission gremlins. I'm thinking something like that would be devastating to our bank account. With enough information, self education, and help from folks like you, I would prefer to do the work myself.

Thanks, and good luck finding and repairing your problem. I'll be waiting to read about the final outcome.

Steve

[RKins]

Dix, I could find the operators manual online but not the service without buying it. There is a lot of good info in the operator manual. Google 3000_4000_operators.pdf

[dix39]

Thank you RKins! There is indeed a lot of info there. Actually, I just found one of these on eBay in paper and bought it.

Since buying this MH a couple of weeks ago without any information/manuals except some maint. records over the last 15-20 years, I've been looking for whatever I can find on the internet and this forum. I would like to find some paper manuals, and I have not so far, but information such as you mention is informative/educational, and I certainly need all of that I can get at this point. That's why I'm following this thread, and any other thread I can find concerning the MH and it's components.

I don't mind buying manuals at a reasonable price. I have shop manuals for all our vehicles including the Flair. A lot of these came from eBay, but I haven't found any there yet pertaining to this MH.

I didn't intend to disrupt the thread, but thought since the posters were knowledgeable about the subject, they might have some idea about where to find information/manuals.

My apologies for any disruption I may have caused.

Steve

[dbarton291]

Allison sells all their manuals at allisontransmissionpublications.com


If you don't want to pay full price sometimes Allison manuals can be found on ebay.

[RKins]

Remember if you find it in PDF you can print it out - take it to a printer and have it double sided and bound. The good thing about a pdf is you can search it.

[dix39]

Thanks guys, I think I have much of the transmission info I need. Now my job is to transfer it from writing to the thing between my shoulders.

Steve