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Topic: Funky door locks and speedo... (Read 1050 times) previous topic - next topic

Funky door locks and speedo...

This is a problem I've had with this car simce I bought it but it seems to be worse now that I installed the FMS pulley kit. The power door locks randomly lock and unlock on their own when the car is running. Also the speedo tends to bounce around between 0 and 20MPH when in gear but sittng still. I had thought it might be a problem with the pos. battery cable as it was a funky looking replacement, but I changed that today and it's still doing it.
 
Any thoughts? Alternator? Voltage regulator?
 
It's starting to drive me nuts.
 
Help?

Funky door locks and speedo...

Reply #1 –
Well, for the speedo. you gears in the trans/driveshaft area are probably shot, or going to be. I would also check all of you grounds in the car, to make sure the nothing is jumping or shorting out.
1987 Cougar XR7 5.0 SOLD
1992 Ranger 4.0
2018 Hyundai Elantra
2019 Ram Rebel

Funky door locks and speedo...

Reply #2 –
Grounds. My headlights would come on and of over bumps. Fix the ground no more worries.

Funky door locks and speedo...

Reply #3 –
Quote from: xr7cat;141727
Well, for the speedo. you gears in the trans/driveshaft area are probably shot, or going to be.

I might believe that if it were acting funny all the time, but it's only when it's stopped, and tonight I saw it jump with the trans in park. I suspect it's electrical and as I said both problems got worse AFTER I installed the pulley kit.

Funky door locks and speedo...

Reply #4 –
i dont have the funky speedometer thing. but i got the same cursed door locks. my car has an alarm system in it, i thought i disabled it(cus its been fine for a year or two) but these last couple months, somehting happened. i see a little red light underneath my dash now(one thats never come on before) and my doors will lock and unlock. i just grew to ignore it now, but i'd look for any alarm systems installed aftermarket
1988 Thunderbird sport
2004 Ford F150 Lariat
2008  Chevrolet Cobalt Sport
2007 Suzuki DR-Z400S dual sport/Supermoto
1988 Thunderbird LX - sold
1988 Mercury Cougar XR-7 with GST kit - gone

Funky door locks and speedo...

Reply #5 –
I have an alarm installed and I haven't completely ruled it out yet. But the alarm doesn't explain the problem getting (both of them) geting worse after the pulley install.

Funky door locks and speedo...

Reply #6 –
If it happened before the pulley install, the pulley install likely isn't the problem ;) It becoming worse may be coincidence, or the lower system voltage might be amplifying the problem.

It could also be (and in fact most likely is) two completely unrelated problems. I've heard of the IVR (instrument voltage regulator) causing some wonky gauge behavior. Could be chaffed wires under the car, could be a bad connection at the speed sensor, could be a bad connection at the cluster (if the printed circuit is corroding)...

The locks are likely caused by the alarm...
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

Funky door locks and speedo...

Reply #7 –
It's probably very unrelated, but my '92 SHO, when I had it, exhibited the strangest bunch of behaviors when the alternator wasn't charging properly.  Airbag light once you go over 20 mph, door locks working intermittently, ATC codes at random.  Very strange things.