Pcm located if my pcm was bad would it cause fuses to draw off the battery

Try unhooking the alternator and check for your draw. A diode can go bad causing a direct draw, but the alternator can still charge. I have had it happen more than once.

say the starter motor is dead and will not crank and starter is silent or clicks or chatters.
the service manual covers this. I have it. 7000 pages.
here is the serial path, the runs the starter
sorry IMMO on jeeps do defeat the starter ,yes spark/fuel.
scan the PCM cranking and it tells you why it fails.
pape 9b-4 in the service manual matches my list.
1: battery main not dead.
all fuses ok.!
2: battery lugs not lose or rusty., Jumper cable jumps fail?
3: key switch not dead.
4: PRNDL switch not bad, (try cranking in Neutral)
5: starter relay bad.
6: starter bad and easy to hot wire test it ask. all shops know how. it is a stnd ASE test.
now a drawing, from 99 SM

the PCM controls the starter motor relay,100%
8w-30-11, SM PAGE., see this.
the PCI bus he TCM tells the PCM transmission is in Park or Neutral SAFE, if not PCM will never close the starter relay or PCI bus is dead, scan the PCm first.
pdc fuse 8 not blown starter power.,solenoid pin.
jb fuse 31 not blown key power.
that is it , a voltmeter can find the point of failure.
key st pin sends crank 12vdc to fuse 31
TRS is transmission PRNDL PCM goes to ground
if tranny in P/N and PCM sees it. else not.


not scanning the PCM is huge fail hear see TCM monitors 3 pins for failures. and more.
even says battery is failing too.

pats is the system that is controlled by your key the pats transponder and the pcm,it is a security system the system is relitivly easy to fix I ask you to please log on to you tube and check out ford focus no start it will explain the easy fix you have to do.I could try to explain it to you but it would be easier for you to watch the video and it will fully explain it to you

Double check the fuses (Inside the car and on engine bay), there is a fuse for the OBDII linkageand sometimes it works together with other systems (Power Outlets, Stereo, Switch, etc). A bad PCM would also cause that but is not very likely.

There are several possibilities. First, the Battery needs to be tested and charged to get the system to its base setting.

There is a cut-out function that works with the PCM and Anti-theft to prevent starting the truck. It will cut the starter voltage to under 7 Volts or less if the battery drops much below 12.6Volts.

So you may be fighting the Anti-theft circuit and it is why the engine does not crank. It also can disengage the charging circuit at Freeway speeds, if the Battery monitor views the Alternators draw to generate power as a parasitic draw.

These 2 nutty features mean your Battery needs to be in the upper 12 volt range or better.

While you may just have a bad PCM, be aware that it may be the victim of these other things rather than the source of your problems.

is it being shorted or overcharging? or is it being drained?

The large MAXI fuses in the engine compartment fuse block are the MAIN fuses. They supply voltage to several other fuses or circuits.

MAXI Fuse #13 in your 1996 Ford Ranger is supposed to be a 30 Amp fuse (not a 50 Amp) according to the power distribution diagrams as well as the fuse block detail diagram. This fuse supplies voltage to the Powertrain Control Module (PCM) power relay and to the oxygen sensor heater circuits.

Please note that it is NORMAL for this fuse to cause a draw on the battery during vehicle operation and also after engine shut down. The OBD-2 oxygen sensor heater circuit monitors run after engine shut down and key off. This can take up to 45 minutes to complete. After the O2 heater monitor has run, the PCM will go into sleep mode.

When the PCM goes into sleep mode, the battery draw from this fuse will be reduced greatly. If you are performing "ignition-off-draw" tests trying to figure out why the battery keeps going dead, it is best to use an ammeter that has a 1 or 2 amp scale. You should set-up for the test using a shunt bar. Wait for 45 minutes to an hour for all of the computer systems in the vehicle to go into sleep mode, then open the shunt. Your computer memory, radio pre-sets, clock, etc. will continue to draw without ever shutting completely off. Any draw under 300 Milliamps is considered "acceptable". It is my experience that most vehicles have an ignition-off-draw of somewhere near 150 Milliamps.

The underhood fuse box diagram can be found on page 314 in the 1996 Ford Ranger Owner's Manual.
If you do not have an Owner's Manual, you can get a PDF version HERE (direct link)

Could be a ground problem; I send you a drain test to check it, you will need a digital volt and ohm meter to perform a battery draw test.

WARNING: Do not attempt this test on a lead-acid battery that has recently been recharged. Explosive gases may cause personal injury. Failure to follow these instructions may result in personal injury.

CAUTION: To prevent damage to the meter, do not crank the engine or operate accessories that draw more than 10A.

NOTE: No factory-equipped vehicle should have more than a 50 mA (0.050 amp) draw.

Check for current drains on the battery in excess of 50 milliamps (0.050 amp) with all the electrical accessories off and the vehicle at rest for at least 40 minutes . Current drains can be tested with the following procedure:

NOTE:
Many electronic modules draw 10 mA (0.010 amp) or more continuously.
Use an in-line ammeter between the negative battery post and its respective cable.

Typically, a drain of approximately one amp can be attributed to an engine compartment lamp, glove compartment lamp, or interior lamp staying on continually. Other component failures or wiring shorts may be located by selectively pulling fuses to pinpoint the location of the current drain. When the current drain is found, the meter reading will fall to an acceptable level. If the drain is still not located after checking all the fuses, it may be due to the generator.

To accurately test the drain on a battery, an in-line digital ammeter must be used. Use of a test lamp or voltmeter is not an accurate method due to the number of electronic modules.

When the battery has been disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module (PCM) relearns its fuel trim. The vehicle may need to be driven to relearn the strategy.

Make sure the junction box(es)/fuse panel(s) is accessible without turning on interior or underhood lights. Drive the vehicle at least 5 minutes and over 48 km/h (30 mph) to turn on and activate the vehicle systems.
Allow the vehicle to sit with the key OFF for at least 40 minutes to allow modules to time out/power down.

Connect a fused jumper wire between the negative battery cable and the negative battery post to prevent modules from resetting and to catch capacitive drains.
Disconnect the negative battery cable from the negative battery post without breaking the connection of the jumper wire.

NOTE: It is very important that continuity is not broken between the negative battery post and the negative battery cable when connecting the meter. If this happens, the entire procedure must be repeated. Connect the tester between the negative battery cable and the post. The meter must be capable of reading milliamps and should have a 10 amp capability.

NOTE:
If the meter settings need to be switched or the test leads need to be moved to another jack, the jumper wire must be reinstalled to avoid breaking continuity.
Amperage draw will vary from vehicle to vehicle depending on the equipment package. Compare to a similar vehicle for reference.
No factory-equipped vehicle should have more than a 50 mA (0.050 amp) draw.

Remove the jumper wire. If the draw is found to be excessive, remove fuses from the central junction box one at a time and note the current drop. Do not reinstall the fuses until you are finished testing. To properly isolate each of the circuits, all of the fuses may need to be removed and install one fuse, note the amperage draw, then remove the fuse and install the next fuse, etc.

If the current draw is still excessive, remove the fuses from the battery junction box (BJB) one at a time and note the current drop. Do not reinstall the fuses until you have finished testing. To properly isolate each of the circuits, all of the fuses may need to be removed. After removal of all of the fuses, install one fuse, note the amperage draw, then remove the fuse and install the next fuse until each circuit has been tested. When the current level drops to an acceptable level after removing a fuse, the circuit containing the excessive draw has been located.

Check the wiring schematic in the wiring diagram for any circuits that run from the battery without passing through the junction boxes. This could find in the Service Manual or Haynes books. If the current draw is still excessive, disconnect these circuits until the draw is found. Also disconnect the generator electrical connections if the draw can not be located. The generator may be internally shorted, causing the current drain.

Hope this helps; also keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using Fixya, and have a nice day.

Is the alternator charging properly.