Heater core repair, days 4-6

Work log - Wednesday

• Retrieved my Helm 1996 Escort/Tracer Electrical & Vacuum Troubleshooting Manual and began reviewing the electrical systems
• Realized how much I have forgotten about reading electrical diagrams
• Reviewed the circuits and changes I made to get the fog lamps to work
• Started a thread at the FEOA web site to get thoughts from others

Work log - Thursday

• Continued reviewing the Electrical & Vacuum Troubleshooting Manual.
• Performed a few basic tests in an attempt to narrow down the location of the issue:
• Disconnecting the headlamp 30A fuse : no headlamp 
• Disconnecting the headlamp relay : no headlamp
• Disconnecting connector C269 : no headlamp
• Labeled a few connectors and wires with a Sharpie permanent marker to keep things straight
• Connector C269, on the steering column, represents the last connector before the multi-function switch (that is, the steering column switch you use to select off/parking lights/head lights). 
• One C269 wire goes to the parking lamp relay and another wire goes to the headlamp relay
• Depending on the position of the multi-function switch, current either does or does not flow through the relays, which in turn control the flow of current to the respective lamps. 
• If I have connector C269 connected, I can use the high/low switch to get low/high beams just fine. So that switch seems OK. 
• The hi/lo switch should get power downstream from the headlamp relay, after the Off/Parkinglamps/Headlamps switch activates it. 
• However, in this case, it does not seem to matter what position I turn the Off/Parkinglamps/Headlamps switch to--the relay powers the headlamps. 

Work log - Friday

• Continued reviewing the Electrical & Vacuum Troubleshooting Manual.
• I would suspect the headlamp relay itself was stuck in the closed position, except for a few facts:
• The headlamps turn off when I remove connector C269
• If the headlamp relay was stuck, it should not matter, and it would still deliver power to the headlamps, if I am thinking correctly. 
• I have shifted my working theory to a ground short in the red wire #7 from the multi-function switch (a.k.a. main light switch) to pin #7 in connector C269 (male side).
• That represents the wire which current flows through to activate the relay. 
• A ground short in that wire would seem to allow current to flow through one side of the relay, which would trip the other side of the relay and allow current to flow through to the headlamps. 
• And a ground short would seem to ignore the setting of the multi-function switch. 
• Replacing this wire seems to imply removing the steering wheel to get at the multi-function switch

Next steps

• I will need to borrow a steering wheel puller from a local parts store
• It turns out Section 17 of the Helm 1996 Escort/Tracer Shop Manual contains pinpoint tests:
• 17-01-11, Pinpoint Test B: Headlamps on Continuously
• 17-01-12, Headlamp switch wire resistance table
• The pinpoint tests largely seem to confirm I am on the right track with my current working theory