POWER WINDOW RELAY RETROFIT
This subject has long been coming and reflects a collaboration with VileZambonie in response to repeated member queries and requests. Our hesitation in posting the retrofit schematic diagrams pivots around our mutual concern that readers might pursue this modification as an end-all to resolve all power window issues.
The modifications described are "functional enhancements" that will not correct or override mechanical problems!!! The model-specific modifications should be pursued only after all mechanical aspects have been thoroughly checked and suitably validated as functioning correctly. In fact, the majority of power window problems derive from maladjustment of tracks, poor lubrication, bent or worn-out parts, and poor electrical connections. At an absolute minimum, to avoid unnecessary expense and disappointing results, window tracks and sashes should be properly adjusted, lubricated, and worn-out parts replaced prior to any modification so that one begins the retrofit with a properly functioning and sound mechanical system!
That stated, IMHO the original design of the power window option was under-engineered, introducing a progressive degradation of function with vehicle aging due in part to the natural and generally unavoidable oxidation of electrical connections, including the unsoldered OEM wire-to-terminal crimp connections, that slowly accumulate unwanted circuit resistance over time. The increased resistance shifts the voltage distribution within the circuit, alters the current flow, and effectively decreases the power supplied to the window motors to the extent that the motors overburden and eventually burn out. In other words, the factory wiring is adequate for showroom trucks but placed into service over long durations the wiring in those originally pristine trucks degrade to the point that high-current appliances, such as power windows, suffer from poor performance. As previously mentioned, some loss of performance nearly always results from poor adjustment, an accumulation of dirt in the window tracks, mechanical wear or distortion, and a loss of lubrication in the mechanism
but, actual motor damage is due largely to insufficient voltage and power starvation.To restore adequate power delivery to the window motors, one can retrofit the OEM power window wiring to incorporate relays that partially bypass the original wiring. There are numerous versions of the basic relay retrofit. The model-specific diagrams illustrated below,
1977 - 1981 (left) and
1982 - 1987 (right), are two of the simpler designs that repurpose the original factory wiring as low-current control circuitry to operate the two UP and DOWN relay pairs (one relay pair for each window). The actual retrofit modification in each illustration is outlined in green. The four relays in conjunction with new 10-gauge load-bearing wires effectively bypass all of the factory wiring, switches, and electrical connections along with their inherent shortcomings to more efficiently supply 30-amp circuit breaker protected power directly to the window motors through shorter wire runs. The result is less voltage loss across the wiring with full electrical power delivered to the window motors.
We recommend that the wire terminal ends affixed to the new 10-gauge load-bearing wires be substantially crimped for strong and reliable mechanical connections and then soldered using electrical grade 60/40 rosin-core solder. Relays can be mounted under the dash. All splices should be burnished as needed, crimped, soldered, and weather-sealed using marine-grade, dual wall, adhesive lined, polyolefin heat shrink. The
1977 - 1981 model trucks benefit from running 10-gauge black ground wires to the window motor frames, as well, grounding independently inside the cab to the respective kick panels up behind the dash.
The
1982 - 1987 left side 2-door window switch uses the wire connector illustrated below on the left. The
1982 - 1987 right side 2-door window switch uses the wire connector illustrated below, center. The
1982 - 1987 permanent magnet power window motors in both doors use the wire connector illustrated below on the right.
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