I'm in the final "under the dash" wiring phase of my custom instrument cluster, populated with Speedhut gauges and a set of LED pilot lamps for warning lights. The vehicle is my 1982 E350 based Class C motorhome and I have the ETVM manual, the shop manual and the service wiring sheets with even more detail than the EVTM. In the course of this rewiring adventure, the color codes of the EVTM have proven largely correct, but the wire distributions at the various numbered connectors must be from another vehicle!

My problem concerns the Parking Brake Warning Indicator. I have a pilot light with the appropriate symbol face for the brake warning light in my custom cluster and I'm trying to tap into the appropriate circuits in the original wiring harness. Studying the EVTM for the 1982 Econoline, on page 42 there is the diagram for both the brake indicator and the oil pressure indicator. In the instrument cluster, there is the brake warning indicator and somewhere else seems to be the parking brake indicator. The diagram shows that the parking brake indicator is only found on the school bus option. Both brake indicators are powered off the run terminal of the ignition switch and both lights trigger with a contact to ground either at the parking brake switch or at the Dual Brake Warning Switch. I therefore intend to to trigger my one Brake Failure indicator light with either a Parking Brake on condition or the failure of the hydraulic brake system. My problem is that there are wires coming from the Start ignition switch position and going to both the Dual Brake Warning Switch and the Parking Switch. This would appear to risk burning out a line from the start ignition switch position, if powered by 12V when the parking brake is depressed. What am I missing?

Oops, I just went back to the Ignition Switch wiring detail and discovered that the circuits 11 and 16 go to ground in the start mode, not to 12V+! Hence this is the light test mode. Need to read more!