Possible Causes

Code 24 will set if there is an open circuit or high resistance in circuits No. 614 or 623 (except Probe) or in circuit No. 944B (Probe). Code 24 will also set if there is low resistance in one or both front impact sensors, or a poor ground exists at terminal No. 3 of diagnostic monitor connector. Intermittent battery voltage at terminal No. 13 of diagnostic monitor can cause reference voltage inside of diagnostic monitor to fluctuate and cause a Code 24 to set in some circumstances.

1. VERIFY CONDITION  - Turn ignition on. Check for fault codes. If Code 24 is flashing, go to step 2). If Code 24 is not flashing, check connectors, wiring, splices and crimps for an intermittent problem. DO NOT  proceed with diagnostic test until code is flashing. Failure to do so will result in needless replacement of diagnostic monitor.
2. DEACTIVATE SYSTEM  - Deactivate air bag system. See COMPLETE SYSTEM DEACTIVATION  under DISABLING & ACTIVATING AIR BAG SYSTEM. Turn ignition off then on. Measure voltage between terminals No. 3 (Black wire) and No. 13 of diagnostic monitor. Record this voltage as system voltage.
3. Using terminal No. 3 as ground, measure voltage between terminal No. 3 and terminals No. 11 and 12 of the diagnostic monitor connector. Using these voltage readings, and system voltage reading taken in step 2), determine if voltage at terminal No. 11 and 12 are within specification. See VOLTAGE SPECIFICATIONS (CODE 24)  . If both voltage readings are within specification, check circuit between fuse block and terminal No. 13 for an intermittent open. Repair as necessary. If wiring is okay, replace diagnostic monitor. On all models except Probe, if both voltage readings are low, go to step 4). If voltage reading at terminal No. 12 is high and voltage reading at terminal No. 11 is low, go to step 5). On Probe, if both voltage readings are low, go to step 4). If voltage reading at terminal No. 12 is high and voltage reading at terminal No. 11 is low, locate and repair circuit No. 944B (Green/White wire).
   VOLTAGE SPECIFICATIONS (CODE 24)
   
   

   Voltage At Terminal No. 11 Or 12	System Voltage
   2.2	10.5
   2.3	11.0
   2.4	11.5
   2.5	12.0
   2.6	12.5
   2.7	13.0
   2.8	13.5
   2.9	14.0
   3.0	14.5
   3.1	15.0
   3.2	15.5

4. CHECK CIRCUIT RESISTANCE  - Turn ignition off. Disconnect diagnostic monitor. On Mustang, diagnostic monitor is located in center console, behind A/C climate control. On Probe, diagnostic monitor is Blue and is located behind left side of instrument panel, near cruise control module. On Tempo and Topaz, diagnostic monitor is located under left side of instrument panel next to fuse block. Disconnect negative battery cable. Using terminal No. 3 as ground, measure resistance between terminal No. 3 and terminals No. 17, 18 and 19 of diagnostic monitor connector. If all resistances are 1160-2000 ohms, go to step 7). If resistance is not 1160-2000 ohms at one or more terminals, go to step 6).
5. CHECK REAR SAFING SENSOR (EXCEPT PROBE)  - Turn ignition off then on. Disconnect safing sensor. See Figure , Figure or Figure . Check for continuity between circuits No. 614 (Gray/Orange wire) and No. 623 (Purple/White wire) of safing sensor connector. If continuity exists, replace rear safing sensor. If continuity does not exist, repair open in circuit No. 614 or 623.
6. CHECK SENSOR RESISTANCE (ALL MODELS)  - Disconnect front impact sensor that resistance reading was not 1160-2000 ohms in step 3). Measure resistance across sensor terminals. If resistance is 1160-2000 ohms, locate and repair short to ground in wiring harness. If resistance is not 1160-2000 ohms, replace impact sensor.
7. CHECK FOR SHORT CIRCUIT  - Using terminal No. 3 as a ground, check for continuity between terminals No. 3 (Black wire) and No. 11 of diagnostic monitor. If continuity exists, locate and repair short to ground in circuit No. 614, 615 or 623 (except Probe) or in circuit No. 944, 944A, 944B or 938 (Probe). Also, check clockspring and safing sensor for internal shorts to ground. If continuity does not exist, replace diagnostic monitor.