Electrical Pats Battery Drain

Discussion in 'SN95 4.6L Mustang Tech' started by Glen gregory, Oct 8, 2012.

  1. Hi Hope someone can help. Have a 98 GT that kills the battery in a few weeks. Traced if down to the PAST in the trunk. If I unplug the last plug towards the rear of the car the drain stops. The remote still locks and unlocks the car,and poops the trunk. No remote start. Anyone have a clue?
  2. A few weeks of sitting and not driving?
  3. Maybe 2 weeks,my 94 cougar and 95 F-150 can sit and never have a problem with them. I know the drain is from the # 8 fuse and traced it to half of the wiring to the trunk mounted PATS.
  4. Disconnect the negative battery cable and connect an ammeter between the cable and neg. battery post. Leave it hooked up with the meter turned on for at least a half an hour. If everything is turned off, key removed, doors closed, trunk closed, hood lamp disconnected (if it has one) the meter should read below 0.1 amps. If it is less than there is nothing wrong with the car other than a possibly weak battery.

    By far the biggest culprit for causing a drain on the battery are add-on aftermarket items such as an alarm or stereo. You Cougar and F150 most likely have batteries with higher rated cold cranking amps, Mustangs have always had smaller batteries than other Fords.
  5. Hi as I said already found the drain,battery is not old and passes a load test.There are no after market add ons. All batteries have about the same cca and rvcap. Its the # 8 fuse. Have been building fords for 30 years I know a bit more then you avg.joe.
  6. If the PATS is the only powered by that fuse then it's possible that there is a stray wire trace or sloppy solder from the flow-solder machine used to manufacture the circuit board. Found a similar problem in one of the EEC modules I've had over the years.
  7. I have seen a lot of posts like this dealing with PATS. My car does the same. I am going to have PATS turned off when I get my car retuned(no clue when). Right now my solution is a disconnect on the neg cable. Going to put my own security on it with GPS tracking soon.
  8. Something I might consider doing if it's a common problem is to wire a relay in-line to the power feed on the PATS. Make that relay close and supply power only when the ignition switch is in the "ON" position.

    Problem solved and PATS would still function. :shrug:

  9. This won't work due to module communication network concerns. The PATS system consists of several modules working in tandem on this car.

    It should also be noted that PATS cannot simply be turned off or disabled.

    Fuse #8 of the interior fuse panel on a 98 Mustang feeds power to one instrument cluster power circuit, partially powers the remote keyless entry module (of which has nothing to do with PATS), certain radio and cd player circuits depending on how equipped, all the courtesy lamps, the trunk lamp, and the power mirrors.
  10. So then it's probably not the PATS that's causing his drain at all.
  11. That would be correct.

  12. Makes the relay idea even better if he's isolated the drain to that particular fuse.
  13. Although I cannot say for certain because I have never attempted to modify one of these specific cars in the manner you described, I would be inclined to think it still would not work. Although the PATS would not be at fault in this instance as far as causing a drain, one of the modules that PATS comprises of on this car is the instrument cluster which I listed as one of the things powered by the #8 interior fuse panel. So you would still have a potential module communication concern causing a possible no start concern, not to mention the RKE wouldn't work properly either.
  14. Unless it would cause the entire car to go "BOOM", I would give it a shot. It's a simple thing to install/remove an inline relay vs. trying to chase down ghosts in the machine. o_O
  15. Well nothing would be damaged by modifying the car in the manner you suggest, but in my opinion it would be a waste of time. A wiring schematic and a basic understanding of electrical theory will diagnose the concern a lot faster. On a 98 Mustang fuse #8 of the interior fuse panel can branch off to as many as 16 different places. If you install the relay immediately after the fuse, you aren't learning anything you don't already know. How do you choose where to install it after that? If you guess wrong, you still don't know anything more, and have done nothing but waste time and cut up a wiring harness. See my point?
  16. Take your alternator in and get it tested.
  17. Lol... wut?

    I think "da PATS" is causing my balls to itch also...

    If "da PATS" offends thee, pluck it out!