asilverblazer

Circuit/System Description The K38A Chassis Control Module-Auxiliary receives inputs from the K133 Trailer Brake Power Control Module; these inputs are used to determine trailer connection and the amount of voltage supplied to the trailer brakes. Conditions for Running the DTC Ignition ON. Battery voltage is 9–18 V. The module is powered up and completes initialization. Conditions for Setting the DTC C111B 03 The trailer brake power control module detects a voltage below a calibrated threshold on the battery positive voltage circuit. C111B 07 The trailer brake power control module detects a voltage above a calibrated threshold on the battery positive voltage circuit. C111B 5A The trailer brake power control module monitors the battery positive voltage circuit. C1595 00 The trailer brake power control module detects a short to ground, open or a short to voltage on the trailer brake control signal circuit. C1596 01 The trailer brake power control module detects a short to voltage in the trailer brake enable signal circuit. C1596 02 The trailer brake power control module detects a short to ground or an open in the trailer brake enable signal circuit. C1114 00 The trailer brake power control module detects a short to ground, open, a short to voltage or a plausibility failure on the trailer brake output circuit. For symptom byte information, refer to Symptom Byte List Action Taken When the DTC Sets C111B 03, C111B 07, C111B 5A The trailer brakes will be disabled as long as the fault is present. The driver information center (DIC) will display a Service Trailer Brake System message as long as the fault is present. C1595 00, C1595 01, C1595 02, C1114 00 The trailer brakes will be disabled for the remainder of the ignition cycle. The DIC will display a Service Trailer Brake System message for the remainder of the ignition cycle. Condition for Clearing the DTC The conditions for setting the DTC are no longer present. The trailer brake power control module clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles. Diagnostic Aids The procedures used in this document are written to diagnose a concern with the customer’s vehicle with no trailer connected. A concern with the customer’s trailer may be the actual cause for a DTC setting or a circuit fault. Some customers may experience an intermittent “Check Trailer Wiring” message and/or a “Service Trailer Brake” message with DTC C1114. These concerns may be caused by a poor connection at the 7–way trailer connector. There are several manufacturers of 7–way (trailer side) connectors and many do not comply with the Society of Automotive Engineers (SAE) standard specifications. Some 7–way (trailer side) connector plugs may not properly engage the truck’s 7–way connector socket and cause open circuits. Also, they may cause deformation and excessive wear of the terminals on the truck’s 7–way connector socket. Over time, this will lead to poor terminal tension between the 7–way (trailer side) connector plug and the truck’s 7–way connector socket. Since the trailer brake control module is always monitoring the vehicle and trailer circuits/components, a poor connection at the 7–way connector may cause a “Check Trailer Wiring” message on the driver information center. Engineering has recommended the use of Pollak Heavy Duty 7–way (trailer side) connector plugs. Pollak is the Original Equipment Manufacturer (OEM) of the truck’s 7–way connector socket. The use of a Pollak Heavy Duty 7–way (trailer side) connector plug will ensure proper fit when the two connectors are mated. If the truck’s 7–way connector socket terminals are deformed or have excessive wear, it will be necessary to replace the truck side connector (use Genuine GM Parts) along with the trailer’s 7–way connector plug using Pollak HD connector plugs. Refer to PIT5311 for additional information. Circuit/System Verification Ignition ON. Verify that DTCs U1505, U1556, U2504, P2534, P2535, or any other communication DTCs are not set. If any of these DTCs are set Refer to Diagnostic Trouble Code (DTC) List - Vehicle. If none of these DTCs are set Verify the Service Trailer Brake System message is not displayed in the driver information center If the Service Trailer Brake System message is displayed and the customer’s trailer is connected to the vehicle Disconnect the customer’s trailer. Verify the Service Trailer Brake System message is not displayed in the driver information center. If the Service Trailer Brake System message is not displayed after disconnecting the customer’s trailer, the circuit fault causing the DTC to set is located in the customer’s trailer wiring harness. This is not diagnosed in service information, nor is it covered by GM warranty. If the Service Trailer Brake System message is displayed after disconnecting the customer’s trailer Refer to Circuit/System Testing. If the Service Trailer Brake System message is displayed and the customer’s trailer is not connected to the vehicle Refer to Circuit/System Testing. If the Service Trailer Brake System message is not displayed and the customer’s trailer is available Verify the customer’s trailer connection is recognized with a Trailer Connected message in the driver information center. If the Trailer Connected message is not displayed when the customer’s trailer is connected to the vehicle Refer to Circuit/System Testing. If the Trailer Connected message is displayed when the customer’s trailer is connected to the vehicle All OK. Circuit/System Testing Note: You must perform the Circuit/System Verification before proceeding with the Circuit/System Testing. The following diagnostic procedure is for factory installed components and wiring on the customer’s vehicle. It will not diagnose a concern with the components and wiring on the customer’s trailer. The following diagnostic procedure is based on not having a trailer connected to the vehicle. Refer to PIT5311 for additional information before using this diagnostic procedure. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the K133 Trailer Brake Power Control Module. It may take up to 2 min for all vehicle systems to power down. Test for less than 10 Ω between the ground circuit terminal 9 and ground. If 10 Ω or greater Ignition OFF. Test for less than 2 Ω in the ground circuit end to end. If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, repair the open/high resistance in the ground connection. If less than 10 Ω Ignition ON. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground. If the test lamp does not illuminate and the circuit fuse is good. Ignition OFF, remove the test lamp. Test for less than 2 Ω in the B+ circuit end to end. If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF, remove the test lamp. Test for infinite resistance between the B+ circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K133 Trailer Brake Power Control Module. If the test lamp illuminates Ignition OFF, disconnect the harness connector at the K38A Chassis Control Module-Auxiliary, ignition ON. Test for less than 1 V between the signal circuit terminals listed below and ground: K133 Trailer Brake Power Control Module signal circuit terminal 2 K133 Trailer Brake Power Control Module signal circuit terminal 5 K133 Trailer Brake Power Control Module signal circuit terminal 8 K133 Trailer Brake Power Control Module signal circuit terminal 12 K133 Trailer Brake Power Control Module signal circuit terminal 14 (if equipped with this wire) If 1 V or greater Repair the short to voltage on the circuit. If less than 1 V Ignition OFF. Test for infinite resistance between the signal circuit terminals listed below and ground: K133 Trailer Brake Power Control Module signal circuit terminal 2 K133 Trailer Brake Power Control Module signal circuit terminal 5 K133 Trailer Brake Power Control Module signal circuit terminal 8 K133 Trailer Brake Power Control Module signal circuit terminal 12 K133 Trailer Brake Power Control Module signal circuit terminal 14 (if equipped with this wire) If less than infinite resistance Repair the short to ground on the circuit. If infinite resistance Test for less than 2 Ω between the signal circuit terminals listed below: K133 Trailer Brake Power Control Module signal circuit terminal 2 and the K38A Chassis Control Module-Auxiliary signal circuit terminal 23 K133 Trailer Brake Power Control Module signal circuit terminal 5 and the K38A Chassis Control Module-Auxiliary signal circuit terminal 22 K133 Trailer Brake Power Control Module signal circuit terminal 12 and the K38A Chassis Control Module-Auxiliary signal circuit terminal 30 K133 Trailer Brake Power Control Module signal circuit terminal 14 and the K38A Chassis Control Module-Auxiliary signal circuit terminal 17 (if equipped with this wire) If 2 Ω or greater Repair the open/high resistance in the circuit. If less than 2 Ω Test for less than 2 Ω between the K133 Trailer Brake Power Control Module signal circuit terminal 8 and the Electric Brakes terminal in the trailer brake harness connector in the rear bumper. Refer to the diagram on the trailer brake harness connector cover for the terminal location. If 2 Ω or greater Repair the open/high resistance in the circuit. If less than 2 Ω Test or replace the K133 Trailer Brake Power Control Module. Verify the DTC does not set while operating the vehicle within the Conditions for Running the DTC. If the DTC sets Replace the K38A Chassis Control Module-Auxiliary. If the DTC does not set All OK.

I think as long as the error is there, you won't get any power on the the brake output wire. I would start inspecting the wiring at the rear, especially the junction block behind the rear bumper. Pull the connectors and check for corrosion.

What have you checked on the trailer? The brake output wire goes from the trailer plug to each hub on the trailer, each hub is daisy chained together. The other wire in the hub is ground (doesn't matter which one). Make sure those grounds are good, and no other wiring issues. Make sure trailer is grounded to the truck - through the plug and hitch ball and if the hitch ball and coupler are old drive it a while to rub the rust off and get a clean connection there too.

My latest truck, which already had new tires on it when I bought it has Goodyear Wrangler Workforce HT tires on it. They are probably fine for a highway tire, but they are terrible on dirt, gravel and leaves. Haven't had them on snow or ice.

Easy - stick with what works.

It'd be nice if the 2nd row captain chairs from the SUV's would bolt in... as you're aware though, the rear wall would be unfinished too, nor would there be room for them to recline either.

Common problem, there is another thread about it, looks like a new switch has just been released (in the las few weeks) that fixes it.

Not disagreeing with your logic - but the results you describe simply didn't materialize at all in my truck, loaded heavy, loaded light, unloaded.

I guess I wasn't as impressed as everyone else... I had them on my 1/2 ton, and the truck rode well. I added the shackles at the same time as I installed new shocks. The two improved ride maybe 10%. The ride was never harsh, I never had any kind of sway problems when towing. I would add them again IF the cost was about 1/2 what they sell for. They worked - but just weren't worth the price to me.

Also have to add that when towing the travel trailer, mpg in my 1/2 ton 5.3 vs. the 1 ton diesel is EXACTLY the same. 9 mpg Unloaded its comparable at 18-19.

I doubt its bottoming out, maybe engaging the overload springs. If it is bottoming out, I want a video of it, because I bet some air is involved.

I don't think one would ever recoup that $10k in fuel savings, range, efficiency or maintenance. All the emissions... $$$ when it starts failing. My better judgment was to get the gasser, because GM's gas engines are (aside from the latest lifter issues) bullet proof. 200-250k miles of trouble free service is the normal. I'll be surprised if I get that out of the diesel, not the engine itself - all the emissions stuff, DEF heaters and injectors, particulate sensors and filters. BUT - I knew if I didn't get the diesel, I'd regret it and wish I did. 900 lb ft...

I had the 5100 on my half ton first, my next 1/2 ton I used the 4600 and wished I used the 5100 instead. The 4600 still allowed more motion in the rear than I prefer. I recall basically the same as what you said that the 5100 were slightly different for larger tires. I recall watching a youtube video that the author claimed information from Bilstein that the differences was negligible as far as internal valving and a normal user would notice no difference between them but continued on with the same idea that a larger tire or lift warranted the use of the 5100. On my 1 ton, I went with 5100 based on results from my 1/2 tons.

Did you switch to a paper or other non-oiled filter? It's not getting too dirty from PVC is it?

Nice to know there are some aftermarket magna-ride shocks, when i had to replace some on a Cadillac a few years ago they were big bucks!

Oiled air filter?

Interest rates are up, who wants a 7% rate when a 2% was the norm not long ago. I'm not seeing anything less than 6.5 around here. That's with "here, take our money" credit too.

Door clicker sounds like a separate problem, maybe the coin battery in the fob or the contacts are dirty underneath. Don't think of it as a "battery" gauge, it's a gauge of the voltage available in the truck, Anything over 12 volts is from the alternator and is to charge the battery. The question you need to be figuring out is why are the lights coming on in the first place? If they are on long enough - they'll run the battery down even if its new.

Sounds like torque converter - but I'd be surprised if that's all it is. Probably going to need a rebuild on the transmission, anything over 150,000 miles could probably use one anyways.

The ones on my truck require a minimum PSI at all times... 5ish if memory serves. I didn't measure to see if that much raised mine any.

I think you're on the right track.

I was thinking along the same lines.

No miss fires? I'd do a compression check and throw a vacuum gauge on it all the basic diagnostic steps... Do those checks cold and warm. Sounds like a bunch of parts have been thrown at it without a thorough diagnosis. Start looking for air/vacuum leaks.

There is another thread about tire pressures that I would suggest (particularly the load inflation tables)... however, your assumptions are correct. If/when I am increasing the weight on any tire I increase its pressure accordingly, up to its maximum pressure/capacity. Below those amounts is some amount of compromise between comfort, fuel efficiency, tire load and tire wear. Empty, right now I am at 60 PSI all around. My heaviest trailer is 10-12000 lbs, I might see how it handles at 60 PSI. Additional PSI would help stiffen the sidewall some, it would also increase the amount of bounce the shocks have to control. The tires start to act like an over inflated basketball if there isn't enough weight on them - load tables above are the key.

That sounds like a shock absorber fix rather than airbags. Previous owner on my truck had the torsion bars cranked WAY up. This made the ride when towing pretty bad. Lower them back down had the best improvement in ride quality. Truck also has airbags on it, I've only got about 5 PSI in them. They seem redundant on my 3500, since its not even on the overload springs when towing. I put on Bilstein 5100s and took a bunch of motion out of the rear end. Also lowered the rear tire PSI down to 60 PSI, running them at 80 had too much bounce (like an over-inflated basketball).