I'm at my wit's end here and really hoping someone can point me in the right direction. My 1999 Mountain High Pinnacle Class A with 76,000 miles on a Ford F-53 chassis has me stumped - ALL four headlights (both high and low beams) just went completely dead, but here's the weird part: every single other light works perfectly. Taillights, brake lights, turn signals, markers - they're all fine.
When the headlight switch is on, there are no headlights at all, and the blue high beam indicator remains constantly lit. I noticed a strange clicking sound from under the hood about every 20-25 seconds, which continued even after disconnecting the coach and chassis batteries.
I've already replaced the headlight switch thinking that was the culprit, but the same problem persists. No headlights whatsoever when I flip the switch, whether I'm on high or low beam. I'm starting to think it might be the combination switch or maybe a relay with a potential dead short, but I don't want to start throwing parts at this thing without some guidance.
Has anyone dealt with this exact scenario on a late 90s Ford chassis? What should I be checking first? I really need to get this sorted out before my next trip.
All headlights out with other lights working points to headlight relay or combination switch failure. Check and swap headlight relay first - if no change, the combination switch is likely failed. Common issue on late 90s Ford chassis.
Your suspicion about the turn signal/dimmer/wiper combination switch is absolutely on the right track for your 1999 Mountain High Pinnacle with the Ford F-53 chassis. The fact that both high and low beams are completely dead while the blue high beam indicator stays constantly lit is a classic symptom of a failed multi-function switch. The relay clicking every 20-25 seconds that only stopped when you disconnected all three batteries strongly suggests the combination switch is creating an intermittent short circuit, causing the headlight relay to cycle on and off repeatedly as it tries to complete the circuit.
What's happening is the internal contacts in your combination switch have likely failed or corroded, breaking the proper connection between the headlight switch and the actual headlight circuits. Since you already replaced the headlight switch itself previously and that fixed the problem temporarily, but now you're getting different symptoms (constant high beam indicator and relay cycling), the combination switch is the logical next culprit in the F-53's lighting circuit.
The Ford F-53 chassis uses a multi-function combination switch that handles turn signals, dimmer control, and windshield wipers all in one unit mounted on the steering column. Over time, especially in a 1999 model with 76,000 miles, the internal contacts wear out from constant use. The dimmer portion of the switch sees heavy use and the contacts can develop corrosion, especially in RVs that sit for extended periods or are exposed to moisture.
The intermittent short circuit you're experiencing happens when damaged internal wiring or contacts create a path to ground that shouldn't exist. This causes the headlight relay to energize briefly, then shut off when the short is detected, then try again - creating that rhythmic clicking sound you heard. The constant high beam indicator suggests the switch is stuck in a position that tells the dash it should be on high beams, even though no power is actually reaching the headlight bulbs.
Your previous headlight switch replacement likely worked temporarily because that switch controls power TO the combination switch, but once the combination switch itself started failing internally, replacing the upstream headlight switch couldn't overcome the downstream problem. The F-53 electrical system is designed with the headlight switch sending power to the combination switch, which then directs that power to either high or low beam circuits based on your dimmer selection.
You made a smart move ordering that $25 combination switch from Amazon - that's exactly the right approach for troubleshooting this issue. Before you start the installation, you'll need a few basic tools: a steering wheel puller (if your model requires wheel removal), a set of screwdrivers including both Phillips and flathead, and possibly a Torx bit set depending on your specific switch mounting. WARNING: Disconnect the airbag system by removing the airbag fuse and waiting at least 10 minutes before beginning work. Ensure you properly disconnect all batteries starting with the negative terminals, then positive terminals to prevent electrical shock or short circuits. Remove any jewelry and avoid contact with metal surfaces.
Take some photos before you start disassembly, especially of the wire connections and their positions. The F-53 combination switch typically has a multi-pin connector, and while it should only fit one way, having reference photos can save you headaches later. Also, grab a flashlight or headlamp because you'll be working in tight quarters around the steering column.
Check your owner's manual or look online for the specific procedure for your year, as some F-53 models require partial steering wheel removal while others allow you to access the switch with the wheel in place. Having the right information beforehand will make this job much smoother and prevent you from having to stop mid-repair to figure out access. Make sure you have the correct part for your model (verify with dealer) before beginning work.
Start by ensuring all batteries are disconnected properly - first disconnect negative terminals on all three batteries, then positive terminals. This prevents any possibility of electrical shock or creating sparks during the repair. Remove any covers or trim pieces around the steering column to access the combination switch. On most F-53 models, you'll need to remove several screws holding the upper and lower steering column covers in place.
Once you can see the switch, locate the electrical connector(s) and carefully unplug them - there's usually a locking tab you'll need to press to release the connector. Take note of which wires go where, though the connector should be keyed to prevent incorrect installation. Remove the screws holding the switch to the steering column (typically 2-3 screws) and carefully pull the old switch out.
Install the new switch in reverse order - position it properly, secure with screws torqued to manufacturer specifications (see service manual for specific torque values), reconnect the electrical connector(s), and reassemble the steering column covers. Before putting everything back together completely, reconnect your batteries (positive terminals first, then negative) and test the headlights. You should now have proper high and low beam function, the high beam indicator should only come on when you're actually on high beams, and that annoying clicking should be gone.
After confirming everything works correctly, finish reassembling any covers and trim pieces. Test all functions - headlights (high and low), turn signals, and windshield wipers - to make sure nothing else was affected during the repair. The entire job should take 1-2 hours depending on your experience level and how easily your particular model comes apart.
If replacing the combination switch doesn't solve your problem, you're looking at a more complex electrical issue that might require professional diagnosis. This could include problems with the headlight relay itself (though the clicking suggests it's trying to work), wiring issues between the switch and the headlights, or even a problem with the body control module if your RV has one.
Another possibility, though less likely given your symptoms, is a problem with the actual headlight circuits themselves - perhaps both high and low beam circuits have developed opens or shorts. A professional would use a multimeter to trace the circuits and identify exactly where the problem lies. Given that your turn signals and other lights work fine, and the relay is clearly trying to operate, the combination switch remains your best bet for a fix.
If you find the combination switch replacement doesn't resolve the issue, don't continue throwing parts at it. At that point, you'll want to have a qualified RV technician or auto electrician trace the circuits with proper diagnostic equipment. The labor cost for professional diagnosis might run $100-200, but it'll save you from buying unnecessary parts and ensure the real problem gets identified and fixed correctly. This methodical approach will get your headlights working reliably again.
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