gcflower

Thank you all for your ideas! Most of the "fixes" described in the forum will work, at least for a while, but the problem will not have been addressed. It certainly hasn't been addressed by GM in either of their TSBs PIT5311A & B (for the different years affected). In fact, GM has the audacity to blame the trailer-side wiring and/or the "...trailer-side connectors that do not meet the SAE specification".!! Why hasn't anyone noticed (or mentioned) that the only trucks having this problem have the 7-way/4-way combo plug oriented with the 7-way on top? GM certainly won't mention it (see below), and you know the folks in the trenches in the Service Departments have probably been told not to say anything to the customer. You know the TSB did not arise out of thin air, but because of a large number of errors arising...with customers who have the combo plug with the 7-way on top. Read on, if you're interested: The real problem, and the reason folks have not had the error with older trucks, Fords, etc. is because GM came up with a great idea that was poorly implemented. They figured combining a 7-way and 4-way plug would save using converter plugs (correct) and save customers having to carry converters for boats and other 4-way wired trailers. Probably a nice gesture overall. However, they did not bother to spec that the 7-way has to be on the bottom of the 7/4 combination plug. If you walk a dealer's lot, you'll see some of the trucks have 7-way on top, others have it on bottom. The truck-side 7/4 combo plug snaps in very nicely to the bumper with its cute little spring clips (another good idea), but the plug can NOT be inverted to put the 7-way on the bottom, where it should be, and like it has been for years. The two bottom terminals in a 7-way, when it is normally oriented with the truck-side lid lifting UP. are the GROUND and TRAILER BRAKE. Hence the problem with GM trucks that have the 7-way on top: as the trailer side plug and wire hang and wiggle (imagine that, what a surprise for the GM engineers!), one or both of the two terminal connections (GROUND &/or BRAKE) can lose contact intermittently, causing the "DING, DING, DING: CHECK TRAILER WIRING" followed shortly by "TRAILER CONNECTED" as the terminals reconnect. This is also why your "Trailer Gain" display on trucks that have that in the info cluster will "grey out" and not show any activity when the connection is loose, then light back up to the normal orange and show activity when the connection is tight. The bumper stamping is apparently done in batches, or perhaps at different locations, resulting in some bumpers having the 7-way hole on top and others with the 7-way on the bottom. Since the plug can not be inverted and GM did not think to spec the bumper stampings correctly, they choose to place the source of the problem with the trailer-side wiring!! Drill and add your own ground wire indeed! Sloppy and lazy on GM's part. Or buy a new trailer-side connector (at your expense), because yours probably "...does not meet the SAE specification". Really?? The REAL fix would be for GM to swap out your current bumper stamping with one having the 7/4 combo plug oriented with the 7-way on the bottom. I can't imagine GM would ever voluntarily do this, unless there were enough safety-related problems &/or accidents involving lack of trailer braking. Why wouldn't GM at least provide the Pollak trailer-side connector to the customer and recommend they visit their favorite RV service center? Or perhaps reimburse the customer for the cost of the Pollak trailer-side connector? All of the affected vehicles are $ 50,000 plus, so a gesture of customer goodwill on the part of GM to really fix this problem (instead of placing blame on the trailer side) would certainly be reasonable. Wait! What was I thinking?! If they can get customers to foot the bill by not being transparent about their engineering snafu (for at least five model years!), nobody in GM has to be accountable. I'm going to buy the Pollak trailer-side plug and start surfing the local and regional salvage yards for a "correctly" stamped bumper. Good luck to you all, Gordon Sacramento, CA