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Having an intermittent problem with my 1985 Fleetwood (FWD). She only turns over about 50% of the time. I’ve tried the classic 3 issues (fuel, air, and spark) and have found no issues. Have been asking around and think it could be my BCM (body control module) but have absolutely no idea where to find that. Any help with the location or what else could be the issue with the car would be greatly appreciated!!
 

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1985 Fleetwood 75
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Having an intermittent problem with my 1985 Fleetwood (FWD). She only turns over about 50% of the time. I’ve tried the classic 3 issues (fuel, air, and spark) and have found no issues. Have been asking around and think it could be my BCM (body control module) but have absolutely no idea where to find that. Any help with the location or what else could be the issue with the car would be greatly appreciated!!
I assume the 4.1 motor you have and cranking? 50% I assume starter is always working but motor just will not fire over but cranks good? BCM part 1226464 behind glove box above heater core box all it does is control temp sensing and coolant fan controls AC blower. You are looking for the ecm it is up under passenger foot well. drop down the under dash cover and you will see an aluminum box stuffed up way in back next to passenger door hinges. you will see three multi pin plugs going into it. Remove neg battery terminal and then try removing and reinstalling ecm plugs to clean off any corrosion on these connectors. They actually slide on to the ecm circuit board foils, and corrosion can set in. Check to see if you have any rust spots above ecm just at the bottom passenger front window corner, is water dripping on ecm box? Pull out ECM and open up the prom cover and remove and re-seat the ecm prom It is a 2732 eprom 24 pin.note orientation pin 1. Again corrosion can cause pin connection problems. Ecm number 1226462.
With motor in run position no start have a fuel pressure gauge on the fuel pressure test port just close to the oil filter you can jumper the oil pressure sender unit it has three contacts on it two are spade lugs opposite each other and one is offset 90* that is the pressure sense for oil light, other two if unplug connector and jumper the opposite spade lugs you can enable fuel pump to run continuously and measure the fuel pressure. should be between 9 and 12 psi. if none you need to fix the fuel pump.
Fuel pumps fail these cars as connector in tank causes arcing in tank, best fix is drop tank and replace the fuel pump with new as well as new fuel strainer as fail item. clean fuel level sender resistor put back together and confirm fuel pressure as before.
ECM only powers fuel pump for about 3 second then the oil pressuresender keeps it going.
Replace the ignition module in the distributor check cap also confirm the pickup wires are good these are failure prone as well ozone corrodes. confirm coil in cap is good and connect from distributor to coil is well mated.
 

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70 Deville 78 Seville 92 Deville 03 Deville
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It sounds like basic battery connections to me. If it is turning over but not starting then I would check the on board diagnostics.
 
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