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Allison - Retarder help needed Diagnostic code 45 26

September 19, 2016, 08:25:27 pm

Following service on the retarder solenoid a few weeks ago I have been getting a series of error codes from the Silverleaf. On today's trip I got a whole slew of new codes from the Silverleaf. See attached.
I hooked up a Nexiq USB-Link and ran the Allison Doc software and it gave me a Diagnostic Code 45 - 26, which equates to "Open Circuit N Solenoid Circuit". I believe the "N" solenoid is the same as the retarder solenoid. The "Open Circuit" text made me think we had pulled a wire out of the 2 conductor plug for that solenoid. But, when I activate the retarder on a trip it works just fine, so I think 12 volts is hitting the coil to send air to the accumulator tank. According to the Allison Troubleshooting Manual the Main Code 45, Subcode 26 does not inhibit anything. And operationally that seems to be true.
So.....
1. Is there any table that will convert Silverleaf codes to Allison codes? The highest Allison code is 70.
2. Where can I go to diagnose the 45 26 code? I ohmed the retarder solenoid at 26 ohms and it seems obvious it is getting 12 vdc. Also removed and reset the connector. Now what?

Thanks, Dick

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Re: Allison - Retarder help needed Diagnostic code 45 26

Reply #1 – October 26, 2016, 06:03:39 pm

To follow up...
I ordered and received a new retarder solenoid. It ohm'ed at at 22 ohms! I now have an expensive spare.
I removed, inspected, straightened pins, and reset the solenoid connector. The code showed up again on the next trip. But this time after the trip the Allison software showed the code had cleared. I spoke with tech support at Pacific Products in WA, the largest Allison service near here. He told me that some codes are cleared after a certain number of ignition cycles. That would explain why for the next three trips there were zero codes. I think the code may have been a one time occurrence. Resetting the connector apparently was all I needed to do. For the last 600 miles or so, no codes.
Hopefully I will have no further problems with this.
Dick

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Re: Allison - Retarder help needed Diagnostic code 45 26

Reply #2 – October 26, 2016, 06:40:05 pm

Dick,

Which codes are the ones that you no longer have - the upper list or the 5 lower that occurred each of the last few trips or all of them?

What service did you do to the retarder solenoid prior to the errors starting?

What caused you to notice the codes?  Do you normally scan the Silverleaf reports or did something appear on the VMSpc screen to alert you?

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Re: Allison - Retarder help needed Diagnostic code 45 26

Reply #3 – October 27, 2016, 08:45:09 am

The code is stored in the slot until it is bumped to the next slot by a new code....unless you clear it---or overtime it may clear. To clear the codes there is a button combination to push, or I'm sure you can use the Nexiq USB-Link. Obviously, it's all moot now since you have the spare!

Slightly off topic, the Nexiq USB-Link....how do you like it? Do you have the allison software and the cummins software for your computer?

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Re: Allison - Retarder help needed Diagnostic code 45 26

Reply #4 – October 27, 2016, 05:36:00 pm

Used to be 50 start cycles to clear memories

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Re: Allison - Retarder help needed Diagnostic code 45 26

Reply #5 – October 27, 2016, 08:13:26 pm

Michelle - The five lower codes no longer show up (the 151 thru 155). Also, they never get saved in the History file. Maybe because they are Inactive?
Same with  the 45 26 Allison code.
The nipple from the retarder solenoid to the accumulator tank broke leaving the solenoid hanging. To insure that doesn't happen again I remotely mounted the solenoid.
I try to remember to look at the Diagnostic tab on VMSpc before I shut off the engine.
Krush - I like the USB Link. I do have the Allison Doc software and Wabco software. The Cummin's Insite software is too expensive and I think may be a subscription. Cummins does have some free software which I have. It will display diagnostic information, but no ability to make any changes to the ECM. That is fine with me.
I have zero expertise with any of these diagnostic tools. My goal was to be able to communicate diagnostic codes to service. Or if possible work on it myself.
Dick

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