My check engine light came on this morning, the Jeep runs fine and I can not tell that anything in wrong, all the gauges are reading correctly also. A couple of days ago my alternator started going bad according to Auto Zone. I went to Auto Zone today because of the Check engine light coming on, and they told me that the code showing is P1698, does anyone know what could cause this code and how I can fix whatever is wrong?

Drew

 

Your computer is having relationship issues -

P1698 No CCD Messages Received From PCM Bus communication failure to PCM. A "Companion DTC" was set in both the ECM and PCM.

 

Ok, does that mean I need a new computer or is something else wrong like a bad sensor some where, and how do I tell?

 

The long winded answer? Take a deep breath, pickup your pencils & scan tools -

P1698 - No CCD Messages received from PCM

Bus communication failure to PCM. A Companion DTC was set in both the ECM and PCM.

DTC P1698: NO BUS MESSAGES RECEIVED FROM PCM

Monitor & Set Conditions
PCM is monitored for receiving BUS messages with ignition on and engine off and with engine running. DTC
may set if there is no communication with the PCM.

Possible Causes

* No Response To PCM
* Open CCD BUS Circuit From PCM To Data Link Connector
* Open CCD BUS (-) Circuit From PCM To Data Link Connector
* Open Ground Circuit
* PCM


Testing
1. Turn ignition on with engine off. Using DRBIII(R) scan tool, try to read DTCs or sensors in PCM. If scan
tool does not display NO RESPONSE to PCM, go to next step. If scan tool displays NO RESPONSE to
PCM, go to NO RESPONSE FROM PCM under SCAN TOOL COMMUNICATIONS.

2. Ensure ignition is on with engine off. Using scan tool, select BODY and select type of instrument cluster
that vehicle is equipped with. Once type of instrument cluster is selected, the BUS operational test will be
performed automatically. If scan tool does not display BUS OPERATIONAL, go to next step. If scan tool
displays BUS OPERATIONAL, test is complete.

3. Ensure ignition is on with engine off. Using scan tool, clear DTCs from Engine Control Module (ECM).
Turn ignition off and then back on again with engine off. Using scan tool, check for stored DTCs in
ECM. If DTC P1698 exists, go to next step. If DTC P1698 does not exist, test is complete.

4. Turn ignition off. Disconnect harness PCM connectors. PCM is located at passenger's side rear corner of
engine compartment. Check for poor connection/terminal contact at PCM harness connectors. Repair as
necessary. Connect jumper wire between ground and terminal No. 30 (Violet/Brown wire) on PCM
harness connector C3. Turn ignition on with engine off. Using scan tool, select BODY and select type of
instrument cluster that vehicle is equipped with. Once type of instrument cluster is selected, the BUS
operational test will be performed automatically. If scan tool displays SHORT TO GROUND, remove
jumper wire and go to next step. If scan tool does not display SHORT TO GROUND, remove jumper
wire. Repair open in Violet/Brown wire between PCM and Data Link Connector (DLC) terminal No. 3.

5. Turn ignition off. Ensure PCM harness connectors are still disconnected. Connect jumper wire between
ground and terminal No. 28 (White/Black wire) on PCM connector C3. Turn ignition on with engine off.
Using scan tool, select BODY and select type of instrument cluster that vehicle is equipped with. Once
type of instrument cluster is selected, the BUS operational test will be performed automatically. If scan
tool displays SHORT TO GROUND, remove jumper wire and go to next step. If scan tool does not
display SHORT TO GROUND, remove jumper wire. Repair open in White/Black wire between PCM and
DLC terminal No. 11.

6. Turn ignition off. Ensure PCM harness connectors are still disconnected. Using DVOM, measure
resistance between ground and terminal No. 31 (Black/Tan wire) on PCM connector C1. If resistance is
less than 10 ohms, replace and program PCM. See appropriate REMOVAL, OVERHAUL &
INSTALLATION article. If resistance is 10 ohms or greater, repair open in Black/Tan wire between
PCM and ground connection. Ground connection is located at ground connection for negative battery
terminal.


Fewf!! Or in English -

Disconnect the negative battery terminal. Check both the fuse block, as well as any fuses related to the PCM & BCM (powertrain control module & Body control module). Look at any fuse connections or plug connections on the PCM itself for any buildup of corrosion. If everything looks decent, reconnect the negative terminal.

 

Wow, and thanks