Automotive Puzzler

jtexas

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I borrowed the title from NPR's "Click & Clack the Tappet Brothers" radio show but this is my own experience.<br /><br />Couple years ago I got hit from behind in my '96 Tbird. About $4,000 in damage including the left taillight assembly. Car still worked, so I drove it a couple days prior to putting it in the shop.<br /><br />One thing I described to the technician was the curious behavoir of the cruise control since the wreck: it worked fine, but soon as I turned on my left turn signal, the cruise disengaged, just as if I had stepped on the break.<br /><br />Month or so later when I picked the car up, I asked about the cruise control. Nothing about it on the work order; I was ready to get mad because he apparently forgot to include it. He suggested we take a test drive to see if it was "still broken." I said, "you mean it might have healed itself?" While driving the car I discovered that the cruise control did in fact work perfectly.<br /><br />Anybody know how this car managed to fix itself?<br /><br />jtw
 

JB

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Re: Automotive Puzzler

Here is what I suspect, jtexas:<br /><br />The CC is disabled by a signal from the brake light switch on the master cylinder.<br /><br />The turn signal uses the same bulb filament as the brake light.<br /><br />The collision damage included shorting the turn signal voltage back to the brakelight switch, making the CC think that you had applied the brakes and turning it off.<br /><br />Repairing the Taillight assembly also repaired the short.
 

LubeDude

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Re: Automotive Puzzler

JB has hit it on the head again!!! That is exactly what happened. I experienced this seveal times in my life as a body man.<br />You the man JB.
 

gaugeguy

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Re: Automotive Puzzler

Elementary my dear Watson ;) <br /><br />I just learned something I didn't know :)
 

jtexas

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Re: Automotive Puzzler

That exactly what the man said! Got it right in one, JB.
 

Dunaruna

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Re: Automotive Puzzler

The brake light & ind. is a shared globe? So the brake light flashes as well - right?<br /><br />Excuse my ignorance, I havn't seen that before (downunder). Is this a recent inovation or have I been living in a cave?<br /><br />Be nice, I learning.<br /><br />Aldo
 

JB

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Re: Automotive Puzzler

Unlike more civilized countries, the US standard rear end lighting has used the same filament for both brake lights and turn signals for years, Dunaruna. It simplifies the wiring and reduces the number (cost) of bulbs used.<br /><br />This has caused numerous problems for folks who wish to connect trailer light wiring to import vehicles. Because all of our trailers use the same system as our vehicles they must buy a lighting adapter with diodes to direct the import style turn signal power to the US style trailer wiring.<br /><br />Recently a few "American" vehicles have switched to the non-American system, causing more confusion for trailer users. I think Dodge trucks are an example.
 

SpinnerBait_Nut

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Re: Automotive Puzzler

My Jeep also uses different circuits for turn and stop.<br />My 1992 Dodge Dakota, as JB stated, does too.
 
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