Troubleshooting electric trailer brakes?

[CoastyAV8R]

I bought our 28" toyhauler last fall and when I drove it home I noticed the brakes were barely working. I found the 7 pin plug had alot of corrosion and when I replaced it I also found 2 broken wires which explained the intermittent light operation. I then pulled the brakes to inspect them and found that the previous owner was over zealous when greasing the bearing buddies so there was grease on all the brakes so I replaced the brakes, installed new seals and repacked all the wheel bearings and adjusted the brakes. (The axles are made by Dexter)



I hooked up to the trailer to take it for a test drive and verified the brake lights work but when I'm driving it the brakes still don't feel like they are working very well. I increased the gain on the brake controller and it made no difference. I don't get the red light on the Hayes brake controller when the foot brake is applied but it does come on when I manually apply the brake switch on the brake controller. When I manually apply the brakes switch on the brake controller I can feel the brakes work but it's weak at best.



What's the best way to troubleshoot the electric brake system on my trailer?



Thanks in advance,



Patrick

 

[B.G. Smith]

If the controller is the inertia type, it may not be positioned correctly to give full application of brakes. The light not coming on sound like the wire to the stop light switch may not be connected or your stop lights on the truck may not have power. Electric brakes are marginal at best, especially the smaller ones. You can have some one hold a compass near the wheel and apply the brakes, the needle on the compass should point to the whhel when brakes are applied. Electric brakes have to be adjusted up pretty close to work right. Don't hold me to this but I think the resistance for four wheel magnets is about 8 ohms checked at the 7 pin connector. Another common problem is the wiring to the wheel where it runs through the axle tubes from one side to the other. bg

 

[RVTRKN]

Does it have the tow package from the factory, you might be missing the relay for trailer brakes. Don't ask me where or what, but I know some have the relays. My 04. 5 & 07 C&C had them with the tow package.



You can isolate it to the trailer or truck by engaging the the emergency brake pull pin, if you pull the pin, your wheels should lock up, because they are getting the full 12VDC signal from the trailer battery to the brakes, if not then you have a wire problem. In your owners manual they give the pin number for your trailer 7 pin connecter plug and the brake wire pin should have 10-12VDC with the brake switch in the full brake position. A good test lite will be able to determine this with the trailer plug in. There are also plugs designed to fool the truck into thinking the trailer plug is inserted, but will lite up for all functions when trouble shooting. I would recommend the later, that way it is a good tool to keep in your trailer for emergencies. I have the proper equipment with me at all times so I just get out multi-meter and check actual voltage.

 

[TMRoper1669]

As stated above, pull the E-Brake on the trailer by removing the black pull pin on the hitch if 12 volts are present then the trailer brakes will lock up unless the magnets on the trailer are not working properly, which is very common. Or there is not 12 volts. Although you can check the magnets by removing the drum and applying voltage, the magnets should hold a wrench. If you have no light on the controller then you need to check that the stop light on the harness to the controller is getting a power feed. Check with a test light. When all check and working properly then there might need to be an adjustment on the brakes itself.

 

[SRadke]

I'd start by checking the voltage at the magnets.

 

[HBarlow]

I... ... ... [snip] I don't get the red light on the Hayes brake controller when the foot brake is applied but it does come on when I manually apply the brake switch on the brake controller. When I manually apply the brakes switch on the brake controller I can feel the brakes work but it's weak at best. [snip]... ... ... ... ... . /quote]

You may have more than one problem. You didn't say but I'm guessing you are using a simple "ramp" type brake controller, not an inertia-based. All electric brake controllers require an input from the brake light switch to initiate every stop cycle. When you depress the service brake pedal you activate this 12 volt switch which illuminates the stop lights. With a factory towing harness it also routes that 12 volt signal to the brake controller. I don't remember the wire color in the towing harness but on all brake controllers it is the red wire in. It should have 12v present when you press the brake pedal down. You are providing that signal manually when you move the trailer brake override lever on the controller.

Poor braking when the manual lever is pressed makes me suspect corroded or bent/weak spring connections in the trailer seven pin male connector or frayed wiring in the trailer wiring run. Have someone press or slide the override lever on the trailer brake controller while you measure voltage at each trailer brake. Did you solder the connections when you installed new brake backing plates? Some trailer manufacturers route the brake wiring down one side of the trailer to one set of brakes then through the axles to the other side. The wires in the axle tubes can fray and short.

If the trailer is used, several years old, poorly maintained by a clueless first owner, and kept in a coastal climate you may have severe corrosion. You could replace the trailer brake wiring and solder all the connections. Somewhere at the front of the trailer the seven pin harness, which is about 5' long, terminates, and individual wire runs to the various lighting loads begin. You could id the brake wire and replace it from that starting point to each brake backing plate.

 

[BDaugherty]

I know it's stupid, but when I bought my trailer, the brakes didn't work at all. I found out not only that the magnets were bad, but they were also installed backwards. I had to swap the brake assemblies from side to side. What I would do:

1. Verify power to the magnets. You could even run a jumper hot wire for testing purposes only. Also verify a good ground.

2. Test magnets. You should have continuity, but I'm not sure how much. They should all be pretty close to the same # of ohms. Make sure each magnet is isolated during the test.

3. Check adjustment of the brakes. If the shoes are backed off too far, you'll get very little braking.

4. Run it a little. When I installed new magnets on mine, I didn't replace the drums. The drums were worn a little where the magnet rides and it took some miles for the magnets to seat.

 

[CoastyAV8R]

Thanks for all the input. I guess I do have 2 seperate problems. I verified the trailer brakes are actually working when the manual switch is used, I may have to adjust the brakes tighter to get them to work better.

Not having the red light come on the brake controller when I push the brakes is the other issue. I'm curious as to why my trailer brake lights come on when I press the brakes but the trailer brakes don't work???

I found I don't have 12v going to the brake controller when I push the brake pedal. My brake lights on the truck do come on except I must have a burned out 3rd brake light as it's not illuminating. I'm curious if the truck's brake switch has gone bad. I guess what i need is the wiring diagram of the brake system to see what exactly I am looking at. Any ideas where I can see the wiring diagram for this?

I do have 12v on the blue wire when I actuate the brake controller manually and the trailer brakes do work when manually actuated.

 

[HBarlow]

The truck's brakelight switch works if the tail/stop lamps are lighted when you press the brake pedal.

Did you verify that the red wire of the brake controller is correctly wired into the towing harness? Does the truck have a factory optional towing brake harness or was it wired, perhaps improperly, by someone? I ordered each of the three Dodges I've owned with the factory option tow package so I don't know how they are shipped w/o the tow package. On the truck's I've owned there is a four pin receptacle under the dash and a four wire harness that extends over to the steering column area and beyond for wiring in a brake controller. Either in the four pin receptacle or at the end of the factory brake controller wiring harness you should find 12v when the brake pedal is depressed. It's routed from the stoplight switch.

As BDaugherty correctly wrote above, brake shoes must be installed correctly and then worn in to mate with the drums then readjusted. If you installed new brake backing plates there are left side brakes and right side brakes. If you simply installed shoes, the magnets should usually be replaced also.

 

[CoastyAV8R]

It has the tow package as it has the blue 4 pin receptacle to the left side of the steering column, it's the 12v that should be there when I press the brakes that I'm missing, the other 3 wires all have what they should have (white is ground, blue has 12volts when I manually actuate the brake controller and black has the constant 12v). What's really weird is I figured I would put a new bulb in the 3rd brake light and the old wasn't burned out but I put a new one in anyway. The 3rd brakelight doesn't come on when I hit the brakes even with the brake controller removed but it does come on when I manually actuate the brakes using the brake controller. I got hold of a service manual and it has a quick way to verify the brake switch is good as it has 6 wires coming off of it with 2 going to the brake lamp circuit, 2 going to the PCM and ABS circuit and 2 going to the speed control circuit. So it's possible that the brake lamp circuit portion of the switch is good but the portion going to the PCM is bad. I may also be looking at a bad PCM since the fuses for the trailer wiring are all built into the PCM, right?

 

[RWinzen]

I hope this helps.



First, I over greased the bearings using easy lube (grease fitting directly at the end of the axel shaft). The service center recommends 4-5 squeezes and that is all. Frequency depends on the amount of miles. Too much grease and the it gets past the seals. It's not like buddy bearings. I had to replace my break shoes because they were too grease'd up.



Second, check the fuse for CHMSL (center high mounted stop light) fuse 24 on my '04. I haven't tested this on the Dodge, but I know from experience on my wife's D-Max. If that fuse blows, the brake controller will not work when the brake pedal is pressed.



If I'm wrong, sorry.

 

[MMoroney]

I found I don't have 12v going to the brake controller when I push the brake pedal.



I do have 12v on the blue wire when I actuate the brake controller manually and the trailer brakes do work when manually actuated.

Have you checked fuse 24 (15A) in the fuse box? It feeds the brake pedal switch contact signal that gets sent to the brake controller. You should have 12V on the white/tan wire at the brake controller connector with the brake pedal pressed.

 

[GaryOwen]

Check out marksrv.com for some good wiring info. I've had several wires on my 03 fail. Appeared they had corrosion inside, but could not detect any break in the outer insulation.

 

[B.G. Smith]

The trailer brakes are operated from a relay in the PDC so they are seperate from the trucks brake lights. The third light may be feeding back through the controller if it is coming on when the manual lever is used. Sounds like you have a fuse blown on the truck for the truck brake lights. bg

 

[CoastyAV8R]

I"m gonna head out and check fuse 24 but before I do, the trucks 2 brake lights work fine, the high mounted 3rd brake light doesn't unless you manual actuate the brake controller. I hope it's a fuse, this stuff here will drive a guy nuts. Corroded/broken wires without a tell tale sign may just push me over the edge chasing those down...

 

[CoastyAV8R]

HOLY COW!!!

Fuse 24 was it! I was wondering what the heck CHMBL was (Center High Mounted Brake Light) as I checked all the other fuses that were labeled with "Brake" in the name. I would have never gotten to the bottom of this without help from all of you so thanks.

I spent all day chasing a fuse down, what a boob...

 

[RWinzen]

Awesome, I'm glad it was something simple. Oo. Chased that one for a day on the D-Max. #@$%! Although it has a relay and fuses for the trailer lights, it still pulls the signal from the CHMSL for the electric brake module. Guess Dodge is the same.

 

[RVTRKN]

CoastyAV8R, looks like a lot of us now know to check out that fuse if we happen to have the same condition. Rwinzen, your experience helped us all, Thanks!