no brakes without fifth wheel battery connected

**RobM** · 04-02-2019, 01:46 PM

I have Titan disc brakes. I can monitor the house batteries on my phone with a victron monitor app. I see a big amp draw on the house batteries when actuating the trailer brakes with the tow vehicle brake actuator. The Titan manual says the house batteries serve to operate the disc brake controller as a peaking battery, and to supply power in a breakaway situation. So, it seems to me that the trailer batteries should supplement the battery draw and help the truck batteries out, not be the sole supplier of trailer brake power.
When I disconnect the negative cable at the trailer batteries and actuate the truck brake controller, there are no trailer brakes.
Is this an error made by the installer when wiring the brakes? I looked at the 7 pin connection junction box, and as has been mentioned before, what a mess. I wouldn't know where to begin, and would do more damage by messing with it.
thanks in advance for any input
RobM

**Jerryr** · 04-02-2019, 07:35 PM

Read this posting from Rob. https://www.mygrandrv.com/fo...-System-Wiring It'd s very well thought out rewire.

I haven't done this yet but it's on my to do list. My installer wired my trailer with Titan brakes per Titan manual. The truck no longer keeps the trailer battery charged. It uses the internal charger in the Titan Actuator to charge the trailer battery. It is a very low current charger. When connected to the truck the Battery voltage is only about 12.8 Volts. When I apply the truck brakes the battery voltage jumps to about 13.8-14 Volts.

**RobM** · 04-03-2019, 01:14 PM

Originally Posted by Jerryr

Read this posting from Rob. https://www.mygrandrv.com/fo...-System-Wiring It'd s very well thought out rewire.

I haven't done this yet but it's on my to do list. My installer wired my trailer with Titan brakes per Titan manual. The truck no longer keeps the trailer battery charged. It uses the internal charger in the Titan Actuator to charge the trailer battery. It is a very low current charger. When connected to the truck the Battery voltage is only about 12.8 Volts. When I apply the truck brakes the battery voltage jumps to about 13.8-14 Volts.

Hey Jerry,
Thanks for the input. My truck doesn't appear to be charging my trailer either. But, when I apply the brakes with the truck's brake controller, I see a discharge of the trailer batteries, and I assume, after a while they will show less voltage. I didn't want to damage anything by holding the lever to actuate those brakes for more than a few seconds. I have solicited Performance Trailer Brakes for input. Advised to check that the trailer batteries are charged, and the connections are good. The trailer batteries are good, but after all day of running the samsung fridge and actuating the trailer brakes, the batteries will wear down.

**RobM** · 04-03-2019, 02:58 PM

I just did an experiment by hooking up the umbilical from the fifth wheel to my 2002 Chevy. What do you know, the truck charges the trailer battery at 5-6 amps, and the trailer brakes successfully actuate without the trailer batteries hooked up. So, the fifth wheel wiring is correct. My 2017 Chevy has all the appropriate 30A fuses installed and not blown..I think they are called "trailer batt" and "trailer pwr." I can only surmise that these new computer trucks appropriately draw current from whichever source it thinks best to run the trailer brakes, and charge the trailer battery when the truck deems it is time.

**Cate&Rob** · 04-03-2019, 04:25 PM

The BrakeRite/Titan actuator is supposed to be powered by a 40A feed from the truck battery. The black wire in the attached diagram. The "emergency apply" is from the "breakaway" battery through the violet wire, the breakaway switch and the brown wire. The violet wire from actuator to breakaway battery is a trickle charge to keep that battery charged.

This all assumes that the breakaway battery is dedicated to emergency brake apply. Like a horse or cargo trailer. This wiring plan does not comprehend a trailer "house" battery that has another high current connection to that same 40A feed from the truck. Because of this connection, if your truck to trailer battery charge current is not there for any reason, you will be powering your actuator with your trailer battery which is not being recharged by the truck.

When I was sorting through all of this with Bill at StopYourTrailer and with Dexter (who now own the trailer disc brakes division of Titan/BrakeRite) they seemed genuinely surprised that no one had ever asked these questions before. The important part of this is that the "factory" wiring diagram leaves the connection between trailer battery and actuator with no fuse or circuit breaker protection. As described in the attachment to post 1 of https://www.mygrandrv.com/fo...-System-Wiring. As far as I know, Performance Braking has never considered this in their wiring of EoH disc brake systems.

(another) Rob

**RobM** · 04-03-2019, 06:16 PM

Thank you Rob. Regarding " if your truck to trailer battery charge current is not there for any reason, you will be powering your actuator with your trailer battery which is not being recharged by the truck." I don't understand why my new truck doesn't seem to supply a charge current to the trailer battery, but my 2002 truck does.
RobM

**Cate&Rob** · 04-03-2019, 07:53 PM

Originally Posted by RobM

Thank you Rob. Regarding " if your truck to trailer battery charge current is not there for any reason, you will be powering your actuator with your trailer battery which is not being recharged by the truck." I don't understand why my new truck doesn't seem to supply a charge current to the trailer battery, but my 2002 truck does.
RobM

RobM,

This sounds like a truck problem . . . not a trailer problem. Earlier trucks needed a fuse and a relay inserted to enable the trailer charging circuit. I think this is software controlled on your 2017. This is a discussion you need to have with your GM Service Department.

Rob

**DaveMatthewsBand** · 04-03-2019, 09:14 PM

Not to deter the thread topic, but does anyone know the charge current?
I would think it would be a set amount regardless of what brand or size your trailer or tow vehicle are.
For instance, I doubt Rob has dual high-output alternators like I do but wouldn’t the trailer wiring be standardized?
So we should both be getting “XX” amps while towing right?
For some reason 15a jumps out at me.

Sent from my iPhone using Tapatalk

**Cate&Rob** · 04-04-2019, 05:52 AM

Originally Posted by DaveMatthewsBand

Not to deter the thread topic, but does anyone know the charge current?
I would think it would be a set amount regardless of what brand or size your trailer or tow vehicle are.
For instance, I doubt Rob has dual high-output alternators like I do but wouldn’t the trailer wiring be standardized?
So we should both be getting “XX” amps while towing right?
For some reason 15a jumps out at me.

The 12V power feed to the trailer connection is fused at 40A on my truck.
When I was installing the trailer disc brake system, I did measure 28A through this wire when the EoH brake actuator starts up.
The current draw to charge the trailer batteries would depend on their state of charge.
The truck system must be able to limit this draw to less than the 40A fuse.

Rob

**TENN22** · 04-04-2019, 06:03 AM

Rob,
If I understand this thread correctly, with EoH brakes installed my truck is no longer able to charge the battery in my FW? Is this a result of wiring incorrectly?Or, is there a way for the truck to continue to charge the battery and have EoH brakes?
FWIW: Performance is installing EoH brakes for me in May. If there is something I need to be aware of or ask specifically I appreciate any input.

Thanks
Brady