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Old 09-29-2015, 08:54 PM   #31 (permalink)
heymccall
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No direct connection.

To the OP, with no test headlamp illumination when using the pedal, but seeing output blocks on the cluster, is indicative of the module either needing reflashed or replaced. At this, I believe that you've diagnosed as far as you can without a scanner attached, verifying module communication. Do you have a friendly dealer nearby? You've tested all of the hardware. It's either a software or module issue.

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Old 09-29-2015, 09:17 PM   #32 (permalink)
padredw
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Well, I've at least learned a lot in the process and am grateful to all who responded--especially to heymccall who kept trying.

I'll just ask one final question. Do the tests we have been able to do poin to the truck rather than the trailer as the most likely source of the problem?

The relevance of that question is this: my truck dealer is in one town and my RV dealer is in another town. Neither is too far away, but it looks like I should take the truck in to the dealer rather than taking the RV. Is my reasoning correct?


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Old 09-29-2015, 09:47 PM   #33 (permalink)
heymccall
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I don't have a truck here right now to verify your results. I'm certain the lamp will illuminate on manual apply, but not sure if it will illuminate with just the pedal. Will have to locate a truck to verify.
Yes. I believe there is a problem in your truck whereupon the TBCM is not receiving or processing a request to increase trailer brake output.
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Its not like I said I enjoyed reading Good Housekeeping while taking a candle lit bubble bath then proceeding to using a loofah with exfoliating creams all while thinking about you . Now THAT would be creepy
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Old 09-29-2015, 09:49 PM   #34 (permalink)
heymccall
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And, if your dealer is skeptical about your headlamp tester, have them try it on any itbc truck, except '14 1/2 tons, and any '15s. Not sure what changed, but, it did. Odds are that your dealer may request the trailer, too, but...it's a truck side issue.
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Old 09-30-2015, 10:17 AM   #35 (permalink)
padredw
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heymccall, I decided on at least one more test with the headlamp so I have an update and a correction:

The lamp does illuminate when the brake pedal is pressed VERY HARD. In the earlier tests we did not press the brake pedal hard enough.

Now the result is this: The light illuminates AND the output meter at the controller is properly displayed under these conditions: any application of the manual controller, and a hard, total pressure on the brake pedal.

I know I seem like a pest, but I'm trying to do all I possibly can before taking the truck or the trailer in for service.

Right now, with the above results, I'm thinking it might be the brake system on the trailer. I had the brakes serviced right before our 2500 mile trip. The report was a broken wire to one of the wheels. We left immediately on the trip and had the brake problem on the last 150 miles just before we got home.

Last edited by padredw; 09-30-2015 at 10:18 AM.
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Old 10-02-2015, 01:16 AM   #36 (permalink)
heymccall
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Thinking about the pedal vs output. With headlamp based tester attached, raise trailer gain all the way up to max, then watch lamp vs output blocks. I think you'll find it takes less pressure to illuminate. Which, in turn, verifies that it is not a truck or itbc problem, but, rather, a trailer wiring issue.
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Brian
'13 Hyundai Genesis Coupe handshaker
'14 Peterbilt 337 handshaker
Quote:
Originally Posted by GetSome8.1HD
Its not like I said I enjoyed reading Good Housekeeping while taking a candle lit bubble bath then proceeding to using a loofah with exfoliating creams all while thinking about you . Now THAT would be creepy
Member #21 of the OiO association
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Old 10-02-2015, 01:08 PM   #37 (permalink)
padredw
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Yes, That's what I found. I have an appointment next Wednesday with the RV dealer to check out the trailer brakes.

I will report back after that to share with the community.

Thanks, mccall, for all the help.

And if anyone in East Texas need a good ITBC tester, I'll be glad to share.
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Old 10-07-2015, 03:22 PM   #38 (permalink)
padredw
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OK, I promised. Now I am here with embarrassment and almost unbelief.

The report: a bad fuse on the trailer end. The fuses were the first thing I checked both on the truck and on the trailer. In fact, I took this fuse out, checked it, and reseated it. Still, that is the report and the proof is in the fact that replacing it was the fix for my trailer brakes. When I talked with the mechanic, he told me that the fuse "looked ok, but was not good."

So, I have learned another lesson on top of all that I have learned here about the ITBC. That lesson: actually try the fuse to the brake wires even if it looks good.

The good news is that my trouble-shooting on the truck system proved to be correct. That was the first thing they ruled out at the RV shop.

Until I am in trouble again, I will be out of here unless I can be of help to someone else.
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