TK Spectrum SB code 35

[shafferLA]

First off, hello from a new member.

A little background, I work for Crete/Shaffer trucking, and generally only see single temp units, most of which are carrier. Lately we have been processing some tri-temp tK units through our shop from a dedicated fleet and I am having a problem with the units. They will pass a running pretrip without problem, but with a standing pretrip, it will almost immediately fail on code 35 (run relay circuit.) This is only on some, and most I have found issues with the current shunt and that cleared up the problem. I currently have 2 that will keep throwing the code 35 even with a freshly rebuilt relay board. I heard something about a software update that widens the acceptable range for current draw, but I can't find anything for sure and my dealer won't volunteer any info, and taking the unit there is not a possibility.

Anybody know about this update, or know anything else that could be the issue?


O ya, and all the wiring tests out good, relay tests good, and run solenoid tests good. Thanks in advance!

[abbsnowman]

Has the alternator been changed? We have had some problems with capadability.
You should try a board test. It's described in the "green book." It will allow you to test each componant individualy and that may help you find the source of issue.

[shafferLA]

Has the alternator been changed? We have had some problems with capadability.
You should try a board test. It's described in the "green book." It will allow you to test each componant individualy and that may help you find the source of issue.


Thanks for the reply. I have done the board tests and found no issues. I will look into the alternator, do you know what p/n it should be?

[shafferLA]

Here at the shop now, alternator is original.

[tkjimmy]

Subject: Alarm Code 35 (Run Relay Circuit) on Microprocessor Units with Thermo
King Alternators

It is possible that the following units will fail the Full Pretrip Test and record Alarm Code 35 (Run Relay Circuit)
and Alarm Code 28 (Pretrip Abort), when equipped with Thermo King alternators (P/N 41-6780 [37 amp],
P/N 41-6781 [65 amp], and P/N 41-6782 [120 amp]).

• Multi-Temp units equipped with μP-IV Multi-Temp Controllers

• SB-400 units equipped with μP-VI Controllers
This happens because units with Thermo King alternators draw less current than units with the Australian Bosch
alternators while the Run Relay Circuit is being tested during the non-running part of the Full Pretrip Test. This
lower current draw causes the software to record Alarm Codes 28 and 35.
The software has been changed to allow for the lower current draw and will not record Alarm Codes 28 and 35 on
units equipped with Thermo King alternators. The following table shows the earliest software revisions that are
compatible with Thermo King alternators.

Controller Earliest Software Revision Compatible with Thermo King Alternators

μP-IV Multi-Temp 2041

μP-VI for SB-400 4320
If a unit equipped with either of these controllers records Alarm Codes 28 and 35 during a Full Pretrip Test, check
the following:
1. Check to see if the unit has a new Thermo King alternator, which is painted black and is identified by a label
on the side of the alternator that lists the amp rating and the service part number.
The 37 amp Thermo King Alternator is P/N 41-6780.
The 65 amp Thermo King Alternator is P/N 41-6781.
The 120 amp Thermo King Alternator is P/N 41-6782.
2. Check the software revision.
3. If the unit has a Thermo King alternator and software earlier than software revision shown in the table, the
software should be replaced with software revision (or later) shown in the table.

IMPORTANT: Software upgrades made to units with previous software revisions are not covered by a warranty
labor allowance. This upgrade is made at the discretion of dealers and with the agreement of the unit owner or
operator.

[abbsnowman]

Thanks TKJ! :cool:

[shafferLA]

Thanks for the help thus far. I have 2 units doing this, both have austrailian Bosch alternators. One has software revision 2022, the other is 2031. I have tried a known good relay board in each, along with a known good Bosch alternator. Still fail standing pretrip right away on code 35. I am going to order a new chip and give it a shot in both to see what I get.

[MRW]

hi check the battery aswell a bad battery could cause problems,,run the unit in high speed cool then run the pretrip,what alternator has it got on it ?if its a 3 compartment then should be a 120 amp alternator,make sure that its a Bosch brush pack in
regards Martin

[bellg]

[quote=shafferLA;214239]Thanks for the help thus far. I have 2 units doing this, both have austrailian Bosch alternators. One has software revision 2022, the other is 2031. I have tried a known good relay board in each, along with a known good Bosch alternator. Still fail standing pretrip right away on code 35. I am going to order a new chip and give it a shot in both to see what I get.[/quote)

What was the final outcome with this problem?

[shafferLA]

Software updates took care of 2 of them, the other is still under investigation. I had a few days off here so I jus got back today. I got rid of the 35 in it, but now I get 40, 29, 105, 106 codes, and all those items work, so I am assuming it is a draw issue on those as well. I threw the charger on the battery while I am shutting the shop down and figured I try it again with a freshly charged battery

Thanks to everyone who has helped!!!