DTC P1493: AMBIENT/BTS V TOO LOW Dodge Ram Wagon B1500

Note. For connector terminal identification, see CONNECTOR IDENTIFICATION . For circuit identification and wiring diagram, see RAM VAN & RAM WAGON wiring diagram in WIRING DIAGRAMS article.

Note. DTC P1493: AMBIENT/BTS V TOO LOW is monitored with engine running at more than 1500 RPM for more than 25 seconds. DTC may be stored in Powertrain Control Module (PCM) when PCM senses voltage from Battery Temperature Sensor (BTS) less than .5 volt or more than 4.9 volts for 3 seconds. Possible causes are: defective BTS defective PCM, defective connector or defective wiring.

1. Turn ignition on, with engine off. Using scan tool, read BTS voltage. If voltage is less than .5 volt, go to next step. If voltage is .5 volt or more, go to step 6).
2. Turn ignition off. Disconnect BTS connector. BTS is located under battery. Clean and/or repair connector as necessary. Turn ignition on, with engine off. Using scan tool, read BTS voltage. If voltage is 4 volts or less, go to next step. If voltage is more than 4 volts, replace BTS. Perform TEST VER-5A.
3. Turn ignition off. Ensure BTS connector is still disconnected. Disconnect PCM connectors. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. Clean and/or repair connectors as necessary. Using an ohmmeter, check resistance between ground and BTS signal circuit (Pink/Yellow wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair BTS signal circuit for short to ground. Perform TEST VER-5A.
4. Turn ignition off. Ensure BTS and PCM connectors are still disconnected. Using ohmmeter, check resistance between BTS connector, signal circuit (Pink/Yellow wire) and sensor ground circuit (Black/Light Blue wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair signal circuit for short to sensor ground circuit. Perform TEST VER-5A.
5. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A.
6. Ensure ignition is on, with engine off. Using scan tool, read BTS voltage. If voltage is more than 4.9 volts, go to next step. If voltage is 4.9 volts or less, go to step 12).
7. Turn ignition off. Disconnect BTS connector. BTS is located under battery. Clean and/or repair connector as necessary. Connect a jumper wire between BTS connector, signal circuit (Pink/Yellow wire) and sensor ground circuit (Black/Light Blue wire). Turn ignition on, with engine off. Using scan tool, read BTS voltage. If voltage is one volt or more, go to next step. If voltage is less than one volt, replace BTS. Perform TEST VER-5A.
8. Turn ignition off. Ensure BTS connector is still disconnected. Connect a jumper wire from sensor ground to engine ground. Turn ignition on, with engine off. Using scan tool, read BTS voltage. If voltage is one volt or more, go to next step. If voltage is less than one volt, repair open sensor ground circuit. Perform TEST VER-5A.
9. Turn ignition off. Ensure BTS connector is still disconnected. Turn ignition on, with engine off. Using a voltmeter, check voltage on BTS connector, signal circuit (Pink/Yellow wire). If voltage is 6 volts or less, go to next step. If voltage is more than 6 volts, repair signal circuit for short to voltage. Perform TEST VER-5A.
10. Turn ignition off. Ensure BTS connector is still disconnected. Disconnect PCM connectors. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. Clean and/or repair connectors as necessary. Using an ohmmeter, check resistance of BTS signal circuit (Pink/Yellow wire) between BTS connector and PCM. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open BTS signal circuit. Perform TEST VER-5A.
11. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A.
12. Turn ignition on, with engine off. Using scan tool, read and monitor BTS voltage while wiggling sensor wiring harness and connector. If sensor voltage changes, repair wiring harness or connector where wiggling caused voltage change. Perform TEST VER-5A. If sensor voltage does not change, go to next step.
13. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. Perform TEST VER-5A. If connectors and wiring harness are okay, test is complete.