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i pulled the codes for my 91 fsb and got a 634-mlps circuit out of self test and 628-converter clutch lock-up error. the tranny sometimes does not engage drive from park(rarely) and shifts alittle hard sometimes. i have 160,000 miles on this truck and thinking about replacing the mpls. is it a tuff job? does the fluid get dumped for this? also, should i replace the vss? and what is the tps i read about in posts? any help is appreciated, thanks
 

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Ex Navy Nuke
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Very easy. The MLPS is the neutral safety switch. Every parts store I called didn't know what the hell a MLPS was but they knew what the NSS was. Make sure you remove the shifter linkage BEFORE trying to remove the bolts for the MLPS or else you will be replacing the shifter linkage(I wish I would've read the write up on here before I replaced mine). No you don't have to dump the fluid, it bolts to the driver's side of the trans. If you still have any problems after the MLPS(like converter lockup or shifting problems) it might be the trans solenoid pack. You will have to drain the fluid and drop the pan if you need to replcae that but first things first. Do the MLPS, make sure you disconnect the battery to get rid of all codes and see if your problem is fixed.
 

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I took mine off and cleaned it, loaded the connector with silicone grease and put it back on. That fixed the occassional hard shift issues I had.

BTW I didn't have to remove the shift linkage on my 91
 

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I was having the same problem. It was shifting hard, and would sometimes seem like it was going ot neutral when I was stepping on the gas , and then engaging.

My best friend after looking at everything said it was the MLPS sensor more than likely . We called and the part is $150 from Ford. So we did the only sensible thing we could do. WE swapped.

Ever since we swapped MLPS sensor's, there have been no issues. I can cruise with no issue and it is not jerking, or sjifting hard, or nothing. SO if you can, find someone who wouldnt mind swapping with you. Takes about 7 minutes to take off. pull the center nut off, slide the linkage off, remove the other 2 bolts. drink a beer, BS a bit, and drink another beer.

Then put the other mlps sensor on your truck in reverse order :D
 

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And have a few more beers:beer :beer
 

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Ex Navy Nuke
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Swatchie said:
We called and the part is $150 from Ford.
:shocked :shocked :shocked

$150 is way too much. $40 or less from NAPA and AZ and Advance.
 

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Steve - I'm having a issue were my trans drops to nutral at highway speeds. The trany was rebuilt in Feb. and I've had it back to the sho[ 4 times and they can never find anything. No codes and it happens intermitenly. Any ideas?
 

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Torvald said:
Steve - I'm having a issue were my trans drops to nutral at highway speeds. The trany was rebuilt in Feb. and I've had it back to the sho[ 4 times and they can never find anything. No codes and it happens intermitenly. Any ideas?
Make sure your connections are good on the MPLS. Clean them and then load it with silicon grease.
 
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