2 no bus codes p0700- no start

Hey so here's my story. I had to replace my ecu earlier in the week due to no guage function and no communication with my pocket scanner as well as with a Matco scanner. I replaced the ecu and gained all dash function back as well as communication with my ecu. My issue now is no bus no communication. I can still read the 3 codes with my scanner but not erase them. I do have injector pulse. The guages work perfect. The no bus is not lighted on the dash. I don't even see the light for it even it was to trigger. The 3 communication codes does not trigger the light. The light only triggers when I pull a sensor. If I were to leave the airbag to the steering wheel disconnected would this trigger this code? The new ecu is a salvage ecu from the same year Heep. Vehicle is a 97 country. Thanks.

I'm hoping just the airbag disconnected would cause this. Otherwise I'm leaning towards reprogram of the ecu to my vin

Exactly, by the numbers, what Check Engine Light trouble codes are, or were, present ?

No communication and gauge issues should lead one to consider a faulty Crankshaft Position Sensor, not a faulty ECU. What diagnostics and testing proved the ECU faulty ?

What does the airbag have to do with the issues, and why is it disconnected ?

If you bought the correct ECU, re-programming is not required.

The first ecu was in fact dead. Nothing worked correctly. No guages and no link with the pcm. I had injector pulse at key on fuel pump always running cruise control stuck on. I pulled the air bag to look into cruise control and left it off. After replacing ecu from same year Cherokee I gained all normal function back. Gauges worked and fuel pump primed for 3 seconds. I am also able to link to PCM now and read codes. Just not erase them. Off the top of my head the codes are 1694 1698 and p0700.

all three code are linked to a TCM failure. Common on the '97.

Will a faulty TCM cause a no spark no start condition?

if its dragging down the CCD bus, yes

What's really making me scratch my head is that I get gauge function and can link to my PCM and read the codes....

The clock spring disconnected will no effect upon the PCM or starting. A faulty CPS can prevent linking with trouble code scanners and is a primary symptom of CPS failure. When the CPS short circuits, the engine computer (PCM) shuts down to prevent damage to itself. As a result, there is no communication (P1694).

P1698 and P1694 at the same time is almost always a failed Crankshaft Position Sensor.

P1694 P1698
http://www.naxja.org/forum/showthread.php?t=63167
http://wiki.answers.com/Q/What_does_code_p1694_mean_for_a_2000_Jeep_Cherokee

P1694 Fault In Companion Module. No CCD/J1850 bus messages received at the power train control module (PCM) from the AisinWarner Transmission Control Module (TCM).

P1694 will set if no CCd bus messages are received from PCM for 20 seconds or invalid messages are received for 20 seconds.

Possible Causes
-CCD Bus (-) circuit open between PCM and TCM.
-CCD Bus (+) circuit open between PCM and TCM.
-Transmission CCD bus wiring damaged.
-Faulty TCM

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

Possible Causes:
- Faulty Engine control Module (ECM)
- Engine control Module(ECM) harness is open or shorted
- Engine control Module (ECM) circuit poor electrical connection

http://www.jeepforum.com/forum/f11/p1698-no-bus-message-transmission-control-module-1359085/

When the CPS short circuits the engine computer (PCM) shuts down to prevent damage to itself. As a result, there is no communication (P1694).

Disconnect your crankshaft position sensor then put the ignition key in the on position. If the instrument cluster voltage and fuel gauges start to work once the CPS is disconnected, then you know the CPS or CPS wires are shorted and is the root cause of the codes. You can verify this by testing the CPS and checking continuity and voltage on the CPS wires.

P1694 Diagnostic Procedure
1. Using scan tool, clear TCM DTCs. Start engine and let idle for at least 2 minutes. Using scan tool, retrieve TCM DTCs. If DTC P1694 returns, go to next step. If DTC P1694 does not return, go to step 5.

2. Check instrument cluster gauges for proper operation. If fuel gauge and speedometer operate properly, go to next step. If fuel gauge and speedometer do not operate properly, see appropriate INSTRUMENT PANELS article.

3. Turn ignition off. Disconnect Gray PCM harness connector. PCM is located at left front of engine compartment. Disconnect TCM harness connector. Measure resistance of CCD BUS (-) circuit (White/Black wire) between TCM harness connector and Gray PCM harness connector. If resistance is more than 5 ohms, repair open in CCd BUS (-) circuit (White/Black wire). If resistance is 5 ohms or less, go to next step.

4. Measure resistance of CCD BUS (+) circuit (Violet/Brown wire) between TCM harness connector and Gray PCM harness connector. If resistance is more than 5 ohms, repair open in CCd BUS (+) circuit (Violet/Brown wire). If resistance is 5 ohms or less, replace TCM.

5. Conditions necessary to set DTC P1694 are currently not present. Inspect related wiring and harness connectors. See WIRING DIAGRAMS. Repair as necessary. If no problem is found, check for broken, bent, backed-out or corroded terminal pins. Check for chafed, pierced or partially broken wires inside insulation. Repair as necessary.

Good write up tim. What tells me the cps is good is that I have gauge function and I did an ohms check across b and c and it checks good. I'll pull the horn relays and fuses and see what that does. Its been pissing raining all day