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engine/steering/electrical/transmission failure??


chun0517
01-22-2004, 01:57 AM
Hi people, I am the owner of a 1996 Mercury Mystique LS with the 2.5L engine/4 spd auto transmission. I'm wondering if anyone can help me out with a few questions...

First, the "check engine" light comes and goes. Recently, it just stays on. I had a mechanic check it out and he said that everything was just fine. If everything is fine, the "check engine" light wouldn't be on, I said. They just said that they didn't find anything wrong and that they couldn't really do anything for me... Mmmm-hmmm...

Likewise, the ABS light comes on every once in a while too...I have no idea why this is happening either.

The transmission is really "jerky". When you press the gas, the revs go up, and then there is a jump as the transmission engages into second gear, and likewise there is another "jump" as it engages into third gear. I've never driven an automatic car that did this, whether it was a new car or an old one.

Electrical systems... The wiring harness under the fuse box just disintegrated one day. I was in the parking lot at work, when the entire car just died, right in the parking spot i was in. A friend messed around with things for a bit, and we found that if you jiggled the fuse box, being a bit loose as it was (which can't be a good thing), that the car would start...if you had a second person helping. The next day though, as i went around a turn, all the lights on the instrument display started flickering on and off, and then everything died at the same time, leaving me to coast onto the side of the road and wait for help. Later I had the wiring harness fixed, and it worked okay for a while, until...

Recently, whenever I try to make turns at low speeds, the engine "shudders" as if it's about to die - the rpm drops to around 500-250, and the steering gets extremely stiff. Sometimes the car just lurches a bit and you can correct this with the gas, other times, the engine dies completely, and i have to stop and then restart the car. This is really disconcerting as the car died last night as i was pulling into another parking lot to pick someone up. What if it had been during the day? I would have collided with whoever was coming from the opposite direction head-on.

I've been reading a lot of comments from Mystique owners online and it seems that this car has a lot of problems... I wish I knew this before I bought this car, as it is too late now (yet not late enough to trade it in...)

Thanks for any input anyone may have...

-Chris

clydes270
01-22-2004, 03:39 PM
All the symptoms point to electrical. Without proper current the transmissions shifts at wrong speeds, the dash lights light intermittently, the car stalls (power steering only lasts for awhile as the drive belts slow - that's why its gets stiff, stiffer, ugh!!!), engine performance is hindered, and the computers (PCM & ABS) also trigger false codes or misinterpret data.

Sensors feed the PCM & ABS, if their readings (voltage) are out of range the PCM and ABS compensate, incorrectly.

Any make or model can encounter electrical problems. Only problem is finding a good mechanic. Troubleshooting electrical problems is not cost productive/profitable. Changing parts is very $$$$.

Here are some guidelines. Maybe what to do for now, or just to keep for future reference.

You've already uncovered one area for electrical. Now, look around there for more. Then, check around the battery to see if nearby wires are corroded or frayed. Get a digital voltmeter and check voltages at the battery. Cheap ones go for $20 at Sears, Home Depot, or

Battery terminal posts before start should be 12.6V. 12.4V or lower is 75% and lower of battery state of charge. Add distilled water to battery cells about 3/4" from top of battery (bottom of shank), then recharge battery to full state. With battery cables on, cover battery terminals/clamps generously with Vaseline.

After start, battery cables (note not the posts were checking connections now) should read 13.5V to 14.5V (ball park can be higher for given alternator series). Add high beams and Max A/C should read the 13.5V at idle or more. If less, don’t suspect the alternator, until you do the following.

Measure voltage from negative battery post to engine block (here some people go – what???). In theory, voltage should be 0V, but that is not practical in the real world. Looking for 0V to 150mV. Anything higher than 150mV, means improper ground from engine block to battery negative post. Clean all ground wires from battery post to nearby sheet metal. Ground screws should always be clean and contact a surface with no paint. Paint will not conduct the electricity. Here the screws thread does the task, as thin as it is. That’s why I remove just enough paint underneath the screw’s head/washer to make adequate ground. Add a dab of Vaseline on the screw head/washer to prevent future corrosion. Tighten or replace all ground straps from engine to firewall, engine to fender wall, etc. Straps can be solid wire, stranded wire, etc.

Measure voltage from positive battery post to alternator positive battery. Refer to Ford manual, Haynes manual, etc. to see which wire to probe/pierce. Like before, ideal is 0V - 150mV. Anything higher means too much resistance through power supply cables. Clean or change positive battery cable, any power splices to terminal block, and any positive leads to fuse panel.

Andrey
06-28-2004, 07:48 PM
[QUOTE=chun0517]Hi people, I am the owner of a 1996 Mercury Mystique LS with the 2.5L engine/4 spd auto transmission. I'm wondering if anyone can help me out with a few questions...

First, the "check engine" light comes and goes. Recently, it just stays on. I had a mechanic check it out and he said that everything was just fine. If everything is fine, the "check engine" light wouldn't be on, I said. They just said that they didn't find anything wrong and that they couldn't really do anything for me... Mmmm-hmmm...

Likewise, the ABS light comes on every once in a while too...I have no idea why this is happening either.

The transmission is really "jerky". When you press the gas, the revs go up, and then there is a jump as the transmission engages into second gear, and likewise there is another "jump" as it engages into third gear. I've never driven an automatic car that did this, whether it was a new car or an old one.

Electrical systems... The wiring harness under the fuse box just disintegrated one day. I was in the parking lot at work, when the entire car just died, right in the parking spot i was in. A friend messed around with things for a bit, and we found that if you jiggled the fuse box, being a bit loose as it was (which can't be a good thing), that the car would start...if you had a second person helping. The next day though, as i went around a turn, all the lights on the instrument display started flickering on and off, and then everything died at the same time, leaving me to coast onto the side of the road and wait for help. Later I had the wiring harness fixed, and it worked okay for a while, until...

Recently, whenever I try to make turns at low speeds, the engine "shudders" as if it's about to die - the rpm drops to around 500-250, and the steering gets extremely stiff. Sometimes the car just lurches a bit and you can correct this with the gas, other times, the engine dies completely, and i have to stop and then restart the car. This is really disconcerting as the car died last night as i was pulling into another parking lot to pick someone up. What if it had been during the day? I would have collided with whoever was coming from the opposite direction head-on.

I've been reading a lot of comments from Mystique owners online and it seems that this car has a lot of problems... I wish I knew this before I bought this car, as it is too late now (yet not late enough to trade it in...)

Thanks for any input anyone may have...

-Chris]

HI
I've got same problems with my 1995 mistake, but there has been campaign for under hood wiring damage #99M03 Limitations 10 years or 100.000 milles.
look in to it

duncandogg
01-26-2005, 05:32 PM
We have a 1998 Mercury Mystique 4 cyl Automatic that started accumulating random problems including an intermittant temperature sender (sometimes reading too high), intermittant check airbag indicator on dash, rough and random idling speed, flat spots on acceleration and premature shifting of the transmission on acceleration. The flat spot looked like a classic Throttle position sensor problem, but this is a low mileage car and the OBD2 check of the TPS looked fine.

One day when the car seemed to be turning over slower than usual, I opened the hood I saw some corrosion developing on the negative battery terminal area that extended down to a ground plate that has multiple ground wires attached to it. This corrosion had not been observed before, but rather seemed to appear suddenly. I removed the entire plate, cleaned the plate and all connections and the terminal with a wire brush, and replaced everything and coated the entire assembly with red battery anticorrosion liquid.

After this cleaning the car seemed to start normally, but interestingly enough the idling issues and flat spot were also gone. The battery post itself was not so corroded as the terminals on the plate, which leads me to conclude that the issues that I was seeing were all related to intermittant grounding at this plate of various electrical sensors and systems. By the way, the airbag indicator problem, temperature indicator and shifting issues have not re-appeared since this repair. Hope this helps someone else out, as this is a simple fix that costs little or nothing and can be attempted by anyone with minimal tools. Remember to always be careful though when working around a battery as not to short the positive terminal to ground! :smile:

cobradude360
01-26-2005, 08:39 PM
the absw light comes on due to some sort of problem in the abs system and the reason the steering gets siff is because the car has power steering and when the car dies its not moveing the belt which would make ur pwr steering pump not work

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