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NHTSA ID Number: 10185733
Manufacturer Communication Number: PIT5747A
Summary
This Preliminary information communicates to dealership how to test properly trailer light option on the truck and also provide additional information on trailer issues.
4 Affected Products
Vehicles
MAKE | MODEL | YEAR |
CHEVROLET | SILVERADO 1500 | 2019 |
CHEVROLET | SILVERADO 2500 | 2020 |
GMC | SIERRA 1500 | 2019 |
GMC | SIERRA 2500 | 2020 |
SEOCONTENT-START
Bulletin No.: PIT5747A
Published date: 12/14/2020
Preliminary Information
PIT5747A Diagnostic Tip – Trailer Lighting Complaints With Trailering App RPO U1D
Models
Brand: | Model: | Model Years: | VIN: | Engine: | Transmissions: | |
from | to | |||||
Chevrolet | Silverado 1500 (New Model) | 2019 | All All All | All | ||
Chevrolet | Silverado | 2020 | All | All | All | All |
GMC | Sierra 1500 (New Model) | 2019 | All All All | All | ||
GMC | Sierra | 2020 | All | All | All | All |
Involved Region or Country | North America |
Additional Options (RPO) | With Trailering App RPO U1D |
Condition | Some customers may comment that their trailer lighting does not operate in the manner expected. Diagnosing these concerns can be difficult because the issue could either be related to the truck or the trailer. This PI is to provide some additional diagnostic information for the symptoms below:
-Trailer lighting is inoperative -Trailer detection is not possible -Trailer lights ash intermittently while the ignition/vehicle is OFF General Information -Any current body style vehicle without RPO U1D, along with all previous model years, are not equipped with a K68 Trailer Lighting Control Module. These vehicles utilize relays to power the trailer connector and do not have features like trailer detection, trailer theft, circuit diagnostics, or bulb outage detection. -Vehicles with RPO U1D, are equipped with a K68 Trailer Lighting Control Module, which powers the trailer lighting circuits to the trailer connector. This provides additional features like trailer detection, trailer theft and trailer lighting circuit diagnostics, such as, trailer bulb outage detection and over current. 2019 Model Year Vehicles – Equipped with U1D use the K68 Trailer Lighting Control Module to control all trailer lighting through pulse width modulated (PWM) voltage. The trailer park, stop/turn signal lamp control circuits must draw at least 55mA of total current to be detected as a trailer or the Trailer Lighting Control Module will not control the lighting circuits to the trailer. 2020 Model Year Vehicles- Equipped with U1D use the K68 Trailer Lighting Control Module to control trailer lighting through pulse width modulated (PWM) voltage to the stop/turn signal and backup lamps. The park lamps utilize an internal printed circuit board (PCB) relay to control the park lamp circuit. This enables additional output current for the park lights. The trailer stop/turn signal lamp control circuits must draw at least 55mA of total current to be detected as a trailer or the Trailer Lighting Control Module will not control the lighting circuits to the trailer.
|
Cause
Root cause can very, follow the information in the Correction section below.
Correction:
When diagnosing a trailer lighting complaint it is recommended to connect the trailer simulator test tool (shown below), GM P/N EL-52641, to the truck’s 7 way connector. The K68 Trailer Lighting Control Module will detect the test tool and enable the trailer lighting outputs. Turn on the ignition and operate all the lights: park, LT/RT turn, stop and reverse. If the lights on the test tool illuminate in correlation with the lights on the vehicle and no DTC’s or warning messages are displayed, then the truck is operating as designed and no repairs should be performed to the truck.
Note: When the ignition is turned o , while the trailer simulator test tool is connected, it may be noticed that the trailer lighting LED’s on the tester flicker/ ash randomly. This is normal and is part of the K68 Trailer Lighting Control Module’s trailer detection/trailer theft features.
Some trailers have wiring that is in very poor condition. A fault on the customer’s trailer may result in DTCs set against the trailer lighting circuits along with DIC warning messages. In some cases, this may even open the K68 Trailer Lighting Control Module Fuse F74UA or F82UA on the vehicle. Verify the customer’s trailer wiring is in good working condition.
If, after using the trailer simulator tester, the truck functions properly, you may follow the diagnostic tips listed below to help diagnose a trailer related issue. Trailer issues are NOT covered under warranty, but this information listed below can be used to help the customer/trailer supplier understand and correct any trailer related issues if they so choose.
- Some trailers utilize a trailer mounted control module to operate some or all of the trailer lights. These trailers may use the B+ circuit from the trailer connector to power the trailer lighting circuits. These trailers may not always be detected by the Trailer Lighting Control Module and may set faults. Possible ways to remedy this:
- Load resistors could be added in parallel to the detectable lighting circuits of the trailer, which will increase current draw. One known source is the Curt brand Trailer Wiring Adaptor P/N 57003, which can be plugged inline with the 7 way trailer connector. This adaptor can be used to simulate additional lighting load, allowing the K68 Trailer Lighting Control Module to detect the trailer, however some circuit diagnostics and bulb outage detection will not be possible. The addition of a load resistor/adaptor will be at the customer’s/trailer manufacture’s discretion.
- The customer’s trailer will need to be rewired to eliminate the trailer mounted control module and have the circuits wired directly to the trailer lamps. This option would allow for the K68 Trailer Lighting Control Module to properly detect the trailer and provide full system features such as, trailer detection, trailer theft, trailer lighting circuit diagnostics, and trailer bulb outage detection. This repair will be at the customer’s/trailer manufacture’s discretion.
- Some non–DOT approved LED lamps may not draw enough current for the K68 Trailer Lighting Control Module to detect a trailer when connected, and the K68 Trailer Lighting Control Module will not enable the lighting circuits to the trailer. Possible ways to remedy this:
- Change one or more trailer lamps on the detectable circuits to incandescent bulbs/ DOT-approved LED lamps to increase the current draw which will maintain full functionality of the K68 Trailer Lighting Control Module. The addition of incandescent bulbs/ DOT-approved LED lamps will be at the customer’s/trailer manufacture’s discretion.
- A load resistor could be added in parallel to the detectable lighting circuits of the trailer, which will increase current draw. One known source is the Curt brand Trailer Wiring Adaptor P/N 57003, which can be plugged inline with the 7 way trailer connector. This adaptor can be used to simulate additional lighting load allowing the K68 Trailer Lighting Control Module to detect the trailer, however some circuit diagnostics and bulb outage detection will not be possible. The addition of a load resistor/adaptor will be at the customer’s/trailer manufacture’s discretion.
- Some aftermarket accessories, such as trailer mounted cameras, are incompatible with PWM voltage and may not function correctly when connected to the trailer lighting circuits of the vehicle. One possible way to remedy this is the lighting control circuits can be wired to control a relay, in which the relay will provide stable voltage to the customer’s aftermarket accessory. This repair will be at the customer’s/trailer manufacture’s discretion.
- With the ignition OFF, the K68 Trailer Lighting Control Module will periodically pulse the lighting circuits of the trailer to verify it is still connected. Depending on the configuration of the trailer lights, the trailer lights may periodically ash as part of the trailer detection and/or trailer theft features. These ashes correspond to when the K68 Trailer Lighting Control Module pulses the lighting circuits to ensure the trailer is still connected and is considered normal. If the periodic trailer light flashing is objectionable to the customer, then engineering released updates to the K68 Trailer Lighting Control Module, see the latest version of bulletin 20-NA-198. After this update is completed, the trailer lights will only ash once every 42 minutes when the trailer theft is turned o . If the trailer theft is on, there will be no change to the timing of the trailer light flashing as the system needs to continuously monitor the trailer connection.
Version History
Version | 2 |
Modified | 06/03/2020 – Created on.
12/14/2020 – Updates to step 4 in the correction. |
SEOCONTENT-END
NHTSA ID Number: 10178307
Manufacturer Communication Number: PIT5747
Summary
This Preliminary information communicates to dealership how to test properly trailer light option on the truck and also provide additional information on trailer issues.
1 Associated Document
Manufacturer Communications
Bulletin No.: PIT5747
Published date: 06/5/2020
https://www.nhtsa.gov/recalls?nhtsaId=10178307
MC-10178307-9999.pdf 281.042KB
1 Associated Document
Manufacturer Communications
Bulletin No.: PIT5747A
Published date: 12/14/2020
https://www.nhtsa.gov/recalls?nhtsaId=10185733
MC-10185733-9999.pdf 281.488KB
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- Tests 7-spade, 6-round and 4/5-flat pin type trailer harnesses
- Short circuit protection
- Turn signal simulation and power verification LED
- Trickle charger and trailer plug adapter included
- Water resistant with an internal battery compartment (Battery not included)
- STRAIGHTFORWARD TRAILER LIGHT TESTING - Simply plug the tester inline between the tow vehicle and trailer, turn on the lights and check the easy to read LEDs.
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- Test 7–way round pin
- Short circuit protection
- Turn signal simulation & power verification LED
- Includes Trickle Charger
- Water resistant with an internal battery compartment (Battery not included)
- 2 in 1 Design. This trailer light tester combines both 4 way circuit tester and 7 way trailer light tester, allows you to test both the 4 pin and the 7 blade connectors. Easy and quick to test trailer circuits on most trucks. ( Notes: 📢The trailer tester will upside down when testing for 2017 Newer Ford/GMC/Chevy model 📢7 pin trailer plug tester is unable to test LED lighting system 📢Doesn't work with vehicle has a lamp-out sensor, such as BMW, VW, Audi, Mercedes-Benz, Porsche etc.)
- Acts as a 7 Pin to 4 Pin Trailer Plug Adapter. 7 way rv trailer tester can be also used as a 7 way to 4 way trailer adapter, converts the vehicle-side 7 pin output to a 4 pin flat adapter to connect the 4 way trailer light plug.
- 6 Light Functions. Versatile trailer wiring tester can be used to test 6 separate trailer light functions, quickly confirm the functionality of taillights, brake lights, reverse lights, turn signals, electric trailer brakes and 12V auxiliary power on your vehicle
- Bright LED Indicators. Plug in 4 way and 7 way trailer light tester equips a LED light for each electrical function. Plugging the light tester and check, you can easily read the green LEDs and find out which wiring has a problem
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- 4 Way Trailer Tester. Using this 4 pin trailer plug tester to confirm proper function of your vehicle’s trailer wiring harness, excellent for diagnosing trailer light issues, lets you know where in the system there is a problem instead of guessing. It also acts as a standard 4-Pin male&female trailer connector to connect standard 4-pin trailer wire.
- Plug & Play. This 4 pin trailer plug tester is easy to use, just plug the tester into the 4 pin flat trailer connector on your tow vehicle and trailer to test taillights and turn signals for proper operation
- Bright LED Indicators. This 4-way trailer circuit tester features a LED light for each electrical functions, turn on the lights and check, you can easily read the LEDs and find out which wiring has a problem
- Durable Construction. 4 pin trailer socket tester is made from durable ABS plastic, which will never rust or corrode. Tin-Plated copper terminals makes great conductivity; Female end tester comes with a rubber dust cover to protect the terminals when not in use
- Compact Design. Small size trailer plug tester is convenient for storage, allows you store in your tool box, glove compartment or anywhere to be ready when you need it. Take this tester to be your assistant when needed wherever you go
- 3 in 1 Design. This trailer light tester combines both 5 way circuit tester and 7 way trailer light tester, allows you to test the 4 pin flat,5 pin flat and the 7 blade connectors. Easy and quick to test trailer circuits on most trucks. Upgraded Double-sided design allow you to read the LEDs from both top and bottom sides! ⚠️⚠️⚠️This trailer tester doesn NOT work with vehicle has a lamp-out sensor, such as 2020+ GMC, Chevrolet, BMW, VW, Audi, Mercedes-Benz, Porsche etc.
- Acts as a 7 Pin to 5 Pin Trailer Plug Adapter. 7 way rv trailer tester can be also used as a 7 way to 5 way trailer adapter, converts the vehicle-side 7 pin output to a 5 pin flat adapter to connect the 5 way or 4 way trailer light plug.
- 6 Light Functions. Versatile trailer wiring tester can be used to test 6 separate trailer light functions, quickly confirm the functionality of taillights, brake lights, reverse lights, turn signals, electric trailer brakes and 12V auxiliary power on your vehicle.
- Bright LED Indicators. Plug in 5 way and 7 way trailer light tester equips a LED light for each electrical function. Plugging the light tester and check, you can easily read the green LEDs and find out which wiring has a problem.
- Durable Construction. For long-lasting use, this 7 blade RV trailer tester is made from durable ABS plastic, which will never rust or corrode. Tin-Plated copper terminals makes great conductivity.
- EASY INSTALLATION & DISASSEMBLY: Simple plug-and-play design, just plug the 7-way trailer plug tester into the connector, turn on the vehicle lights and signals, then check the LED lights on the tester. Each of the indicator light with clear labeling to tell you which of your towing vehicle lights work or not. No extra tools or batteries needed, simple and easy, that's it.
- LONG-LASTING CONSTRUCTION: The tough nylon body and copper terminals, provide excellent water/high temperature/wear/corrosion resistance, extend the life of the 7 way trailer plug tester.
- MULTIPURPOSE USE: This 7 pin trailer plug tester tests for taillights, brake controller output, back up or reverse circuit center pole, right turn/brake, left turn/brake and 12-volt power feed. Tests 6 separate trailer light functions.
- WIDE ADAPTABILITY & 1 YEAR WARRANTY: No need for multi plugs to tow various vehicles, it works for nearly all the common 7 way trailer plug used on most SUV's, Trucks, Boats, Trailers Campers, Caravans, Food Vans and other Towed Vehicles. Besides, there is 1 year warranty for the seven pin trailer plug tester. Both are quite practical for drivers.
- PRACTICAL DESIGN: Small size for easy carrying, this trailer light tester can be stored in a glove box or tool box, no spare space need to be taken up.
- Fits 4-Pin Small Size Trailer Light Tester & Circuit Troubleshooter, Quickly and easily see if your trailer wiring is properly installed on your vehicle
- Small size fits easily in gloves compartment or pockets, No Batteries Required.
- 4 Pin trailer testers: ABS+ Coppers materials, with TAIL,LT,RT lights
- Test right, left, turn, and brakes lights for proper functions.
- Easy to carry, Compact Designs Fits in your pocket. If you have any questions please contact us first and we will give you 100% Satisfaction Guaranteed.
- Easy to use
- Has a typical lifetime of 10+ years
- Checks if the vehicle's tow circuit is properly configured
- ✨EASY INSTALLATION & DISASSEMBLY: Quick plug-and-play functionality. Simply insert the 7-way plug tester into your trailer's connector, activate your vehicle's lights and signals, and check the status of each LED indicator—no tools or batteries necessary.
- ⚙️LONG-LASTING CONSTRUCTION: Crafted with a robust nylon body and high-conductive copper terminals, our trailer plug tester is designed to resist water, high temperatures, wear, and corrosion for a longer lifespan.
- 💪MULTIPURPOSE USE: Test 6 different trailer light functions with a single device. Our 7 pin tester checks your taillights, brake controller output, reverse circuit, turn signals, and the 12-volt power feed—ensuring all lights function correctly before you hit the road.
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- ⏳PRACTICAL DESIGN: Compact and easy to store. The tester's small size makes it perfect for keeping in your glove compartment or tool box, ensuring it's there when you need it without taking up unnecessary space.
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