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Weird Electrical Issue


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MCSE
Novice

Oct 7, 2006, 9:49 PM

Post #1 of 10 (1941 views)
Weird Electrical Issue Sign In

I have a 1996 Mercury Sable GS.

Since purchasing it the Check Engine Soon light would intermittently turn on. We had the car checked and there were no error codes and the light would eventually turn off. This light has not turned on again for at least a month so it appears that the issue has fixed itself. Anyway, this is not my concern but thought I would try to be as detailed as possible.

The problem is this. When my car is started and running in Park all the electrical systems operate correctly. As soon as my car is placed into gear I lose my power windows, power steering and radio. I have checked all the lights(turn signals, brakes, headlights, interior lights, etc) and they continue to work fine when this issue occurs. Today, the seat belt light started flashing for about 30 seconds even though we were all "buckled up". What is really strange is that every now and then(maybe 10% of the time) the problem disappears and everything operates normally.

As well, sometimes(very rarely) the car will fluctuate in speed on the highway when in Cruise Control. When this occurs, you can see the rpms going quite high(not in the red though).

Is it not strange to have such selective electrical issues? Would not the lights be affected too? I have talked to some mechanics but they seem to have never seen this issue before. Any suggestions?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 7, 2006, 11:49 PM

Post #2 of 10 (1935 views)
Re: Weird Electrical Issue Sign In

Egad! Check for the code if any and see if that is telling. This stinks as intermittent problems are about as much fun as fixing Christmas lights that act up sometimes and you touch them and they work so WTF are you supposed to do?? ( the F stands for Fun)

This is Murphy's Law and this problem will like some others never do it when a tech is looking and this stuff causes hair loss for all concerned.

It's near impossible to fix what isn't broken?? Hope that it will stay broken for the fix or go away and I'm at a loss for more suggestions. Good luck and let us know what you find, T



steve01832
Veteran
steve01832 profile image

Oct 8, 2006, 4:45 AM

Post #3 of 10 (1934 views)
Re: Weird Electrical Issue Sign In

The only thing I could think of is maybe a Body Control Module issue. Possible ground splice loose or corroded. This doesn't explain the loss of power steering though. Check for codes and see if the other computers are communicating with the PCM. There is a definite ghost in the machine here. Also, just for fun, check the charging system and battery while these awesome events are happening.

Steve


MCSE
Novice

Oct 8, 2006, 7:17 AM

Post #4 of 10 (1933 views)
Re: Weird Electrical Issue Sign In

Thanks Guys.

I shall check out the things mentioned and let you know what I find. Unfortunately, the mechanic does not have an opening until Friday so I guess I will have to wait on the codes.
I will let you know how things turn out.

I greatly appreciate all your help :-)


DanD
Veteran / Moderator
DanD profile image

Oct 10, 2006, 4:20 AM

Post #5 of 10 (1917 views)
Re: Weird Electrical Issue Sign In

Replace the neutral Safety switch or as Ford calls it the transmission range sensor. This is a fairly common problem with Taurus and Sables that something shorts inside the sensor sending the Body Control Module the wrong signal. Causing all of the strange things you mentioned to happen.
The steering on these things Steve are variable rate and when this short happens the BCM commands the power steering assist to go into requiring more effort to turn the wheel as if you were travelling at highway speeds.
Dan.

Canadian "EH"






MCSE
Novice

Oct 10, 2006, 8:28 AM

Post #6 of 10 (1912 views)
Re: Weird Electrical Issue Sign In

If this ends up being the issue then you should consider yourself a mechanical guru! You are the first person who has been able to place your finger on a specific "fix" and you have not even seen the car in action.

I shall do what you mentioned and let you know the results. I can't get the car in until Friday so it will most likely be Saturday when I inform you of the results. Thanks alot I really appreciate it!


MCSE
Novice

Oct 10, 2006, 7:02 PM

Post #7 of 10 (1902 views)
Re: Weird Electrical Issue Sign In

I was just wondering if you would consider this type of work(replacing the Transmission Range Sensor) a do it yourself job? Is it fairly easy to do and is it fixed from the hood or from under the car.

I love being able to fix my car when it is practical(the basics...like new alternator, oil changes, new starters, etc) but if this work involves a lift or transmission jack then it soon becomes impractical...lol. As well, if this job is done from under the car then I would rather have someone with a lift do it. The autozone website seems to suggest that it is done from above(under the hood)...I Hope so.

If you feel that this job could be done by someone who is mechanically proficient then please let me know and I will purchase a Chiltons and get to work. Once again, thanks for all your help and invaluable expertise.


DanD
Veteran / Moderator
DanD profile image

Oct 11, 2006, 3:38 AM

Post #8 of 10 (1899 views)
Re: Weird Electrical Issue Sign In

You’ll find the range sensor under the hood on top of the transmission below the shifter mechanism. If you’re not sure where the shifter mechanism is have a helper shift the trans for you while you’re having a look. Another good idea is to have the replacement sensor before you begin. That’ll give you a chance to study it and understand what, where and maybe how it works. It is an adjustable sensor but if you match mark the new sensor to the old sensor’s bolt markings it should be close enough to work.
You may have to tweak the sensor one-way or the other but if the engine will start in park or neutral (only) then you should be fine.
Dan.

Canadian "EH"






MCSE
Novice

Oct 23, 2006, 3:20 PM

Post #9 of 10 (1865 views)
Re: Weird Electrical Issue Sign In

You have shown great expertise and helpfulness and I thought it was only fair to let you know that you were right. I switched out the Transmission Range Sensor and now everything is working great. Thanks for your help. It was greatly appreciated. I wish we had mechanics around here who are so adept as what you have shown.


DanD
Veteran / Moderator
DanD profile image

Oct 23, 2006, 5:09 PM

Post #10 of 10 (1862 views)
Re: Weird Electrical Issue Sign In

Thank you for the fix reply; that’s what makes coming here worth while.
My biggest reason for frequenting this site is that if I can explain things here on a keyboard then hopefully I’ll be able to in person with my customers.
The more they understand what I/we have had to do to repair their vehicle the easier my job will be. Especially when; I have to hand them their repair invoice; Ouch!
As long as people understand what they are paying for; the easier it is for them to swallow.
My/our trade is full of misconceptions that every vehicle is the same and when a layman hears a certain issue then they think this has to be blah blha blha; this is all you need. I call that bar room repairs a lot of talk and no won has to prove their statements.
Thanks again for the fix.

Dan.

Canadian "EH"










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