Light came on when my battery went dead. Code 52 is back-up power supply circuit. I have since replaced battery but light has not gone off. Any ideas

 

I don't know what year your truck is but there is a fuse that supplies the Air bag system that may now be open.
There is a large value capacitor involved with the system that once discharged will take a large amount of current upon inital power up. This may have blown the fuse.

 

All fuses are OK both under dash and in engine compartment
Vehicle is 98 with 4.6

 

is the air bag deactivation switch light on?????? if so that is your problem and change the switch....

 

Code 52 lists this:

B1867 12/52 Lost or low battery voltage GO to Pinpoint Test A.

Here's what the manual had to say about it: (Accent added)

Pinpoint Test A: LFC 12/52/DTC B1867 — Lost Battery Feed or Low Battery Feed Voltage

Normal Operation

The air bag diagnostic monitor (14B056) measures the voltage at Pin C209-14, Circuit 937 (R/W). The voltage at Pin C209-14 should be equal to battery voltage. If the voltage at Pin C209-14 drops below 8 volts, the air bag diagnostic monitor will flash a lamp fault code (LFC) 12 on the air bag indicator. If the voltage at Pin C209-14 drops below 5 volts, the air bag diagnostic monitor will store diagnostic trouble code (DTC) B1867 in its memory. <b>Should the loss of battery voltage at Pin C209-14 be intermittent or repaired, the air bag diagnostic monitor will flash an LFC 52 (or higher priority code if one exists) on the next ignition switch cycle.</b>

Possible Causes

WARNING: Do not under any circumstances substitute another fuse value for the power distribution box fuse 2 (10 a). Any fuse other than 10 a can cause disarming failure and can result in danger to the occupants of the vehicle. Do not attempt to replace the power distribution box fuse 2 (10 a) unless the battery ground cable has been disconnected and the backup power supply energy has been depleted. To deplete the backup power supply energy, disconnect the battery ground cable and wait one minute. Be sure to disconnect auxiliary batteries and power supplies (if so equipped).

NOTE: If a short to ground exists on any of the air bag module Circuits 607 (LB/O), 614 (GY/O), 615 (GY/W), or 616 (PK/BK), leading to a lamp fault code (LFC) 13 or 53 and a diagnostic trouble code (DTC) B1913; or, similarly, a short to ground exists on any of the air bag sensor circuits 617 (PK/O), 619 (PK/W), 624 (Y/W), or 625 (Y/LG), leading to an LFC 14 or 54 and DTC B1914, the air bag diagnostic monitor will activate an internal solid state switch at Pin C209-13 of the air bag diagnostic monitor. The activation of this switch shorts Circuit 937 (R/W) to ground, causing the power distribution box Fuse 2 (10 A) to open, thus disarming the air bag supplemental restraint system (SRS) and preventing inadvertent air bag deployment.

Lost battery feed voltage at Pin C209-14, Circuit 937 (R/W) can be caused by:

an open in Circuit 937 (R/W).
an open in the power distribution box Fuse 2 (10 A).
an open in the circuits feeding the power distribution box Fuse 2 (10 A).
a short to ground on Circuit 937 (R/W).
Low battery feed voltage at Pin C209-14, Circuit 937 (R/W), can be caused by:

A concern in the charging system causing battery voltage to drop below 8 volts.
After the air bag diagnostic monitor has disarmed the air bag system, it will not be enabled to disarm again until the appropriate condition (DTC B1913 or B1914) has been repaired and cleared by performing the appropriate pinpoint tests.

I can post the rest of the diagnostic, but it involves an NGS tester, and I doubt anyone has one in their garage.

-Joe

 

As you see by the test info just given, care has to be used on this system.
The Haynes book won't even address this feature because it is a high saftey concern that has life saving implications if it does not work.
If the system does not work in an accident that should have triggered the bags, all kind of questions arise from the insurence company!!!!!!!
Good luck.

 

I don't recommend someone working on SRS systems who doesn't know what they're doing...as much as I hate to say it, might want to take a trip to your friendly neighborhood Ford dealer.