1988 Toyota Trailer Wiring | etrailer Recommended Trailer Wiring Harness for 1988 Toyota Pickup; We do have a couple universal harnesses that are confirmed to fit, however there is not a custom, plug and play style wiring harness available for your 1988 Toyota Pickup. To install a 4-Way connector, I recommend the Tekonsha Upgraded Circuit Protected ModuLite Harness # 119179KIT. 1988 Toyota 4Runner OE Wiring Harnesses & Stereo Adapters Toyota 4Runner 1988, Aftermarket Radio Wiring Harness by Metra®, with OEM Plug. For aftermarket stereo. Metra preassembled wiring harnesses can make your car stereo installation seamless, or at least a lot simpler.