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Check your lamp control relay Posted by sam96CS [Email] (#852) [Profile/Gallery] (more from sam96CS) on Tue, 10 Aug 2010 14:46:58 In Reply to: Right HI Beamot working, AEro, Tue, 10 Aug 2010 12:05:01 Members do not see ads below this line. - Help Keep This Site Online - Signup |
It's probably your lamp control relay, a large square orange relay located under the hood near the battery. You can replace it for $45 or maybe fix it. Maybe my notes below will help. Sam
The lamp control "relay" isn't a relay at all. It checks the flow of current through the headlights and flashes an alarm on the Pictogram if a bulb is burned out. In theory anyway. The part is prone to solder failure where the 8 pins are soldered to the circuit board, and this is especially true of the 3 pins associated with the high beam. You need a mangifying glass to see what you're doing.
First remove the orange cover. It has tabs on 3 sides. I found I could not lever the tabs over the base without the risk of the case spliting. So I removed one tab from the opposed pair with a box cutter. Then the other two tabs could be pried and levered with two small screwdrivers. This reveals the pcb which is vertically attached to the plastic base and terminals. The pcb is soldered to the end of the terminals which extend over and through the base to its edge.
The pins are identified and assigned as follows:
56a feeds both 56aR and 56aL (High Beam),
56b feeds both 56bR and 56bL (Low Beam).
31 is linked to c2 and runs through a transistor - so it needs handling with more care. (You will not get any current to flow here unless you unbalance one pair of the lamp feeds through a load - which would then bias on the transistor).
Use a multimeter to check resistance as follows:
There should be no resistance between 56a and 56aR (high beam right side)
There should be no resistance between 56a and 56aL (high beam left side)
There should be no resistance between 56b and 56bR (low beam right side)
There should be no resistance between 56b and 56bL (low beam left side)
What I found was infinite resistance between 56a and both 56aR and 56aL. This makes sense because neither high beam worked. The solder at 56a looked cracked. So I put the relay innards on the stove top between the two rear burners with a heavy salt shaker behind it (using the burner rings and salt shaker to keep it from moving when touched with the soldering iron. I plugged in the Weller model SP-23 iron (25 watt) and waited 5 minutes for it to get hot - the handle was warm to the touch close to where it flares. I turned on overhead light and exhaust fan. I heated the 3rd pin, which corresponds with 56a, applying the tip of the Weller to the base of the pin. It smoked just a little when the old solder melted. After that I had continuity between 56a and 56aR, but I didn't have continuity between 56a and 56aL. So I heated the 1st pin, which corresponds with 56aL until I got a little wisp of smoke. Now there is continuity between 56a and 56aL.
It can be tested before replacing the cover by plugging it about 3/4 of the way into the socket. Be gentle when removing it, apply force to the base rather than to the pcb as much as possible (I removed the headlight relay to make the base more accessible).
Now both high beams work, and so does the blue high beam indicator light on the instrument panel. If either high beam fails to turn on, the Pictogram correctly shows there is a headlight problem (without giving any specifics).
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