1996 ford explorer no start problem(engine cranks) hooked snapon redbrick scanner w/ no communication, also no self test. power to and thru pcm relay, power to fuel pump relay but relay not triggered.Testlight on grd touched 2 f/p relay on Ltblu/orange wire activates relay,turns f/p on but no spark,crank sensor shows .9v ac when cranking.Dont know what resistance value should be.What am I missing? Please help, FYI I am an 20 yr ASE cert GM tech w/ a few hour of electrical training. Thanks 2 all

ETC - electronic throttle control problem .

P0606 - Powertrain Control Module (PCM) Internal Communication Error Description: P0606 indicates a register readback (PCM internal communications) error. Possible Causes:

• Damaged PCM.

Diagnostic Aids: Internal PCM failure. Install a new PCM.
For Electronic Throttle Control applications, an internal PCM failure, or an ETC system FMEM condition exists. Repairing the other DTCs can fix the P0606. Application Key On Engine Off Key On Engine Running Continuous Memory Vehicles With Electronic Throttle Control (ETC) The DTC is an indication of a failure mode in the electronic throttle control system, which includes the accelerator pedal position (APP) sensor, electronic throttle body (ETB), and powertrain control module (PCM). It is accompanied by other DTCs which provide repair direction. Diagnose and repair those DTCS, and the P0606 will not be reset. All others Make sure to check for aftermarket performance products before installing a new powertrain control module (PCM). If it is necessary to install a new PCM, refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM).

What do you mean won't start ? When you turn the key to start the starter won't engage an spin the engine ? Anti-theft light lit or flashing ? How do you know no power to instrument cluster ? Did you check power an ground circuit's for the cluster using a DVOM - digital volt ohmmeter. or is it nothing lights up. A dead instrument cluster can cause a no crank - no - start condition . Bring down serial data buss . All the modules on the vehicle - PCM - engine computer , Body control module , ABS , air bag's etc... all communicate (talk with ) share info. on this serial data buss . If the PCM loose's communication with the PCM , the PCM will not energize the starter relay .

Its very possible the computer is dead. A mechanic would pin test the computer plugs to verify it has power and ground.
Does the check engine light come on when the key switch is turned on ?

There are hundreds of ground connections on a van.
If the check engine light is not coming on, and a scanner is not working, and you know for a fact the EEC relay is working, I would check the connections on the PCM.
You may need to get a shop manual to be able to pin test the PCM.

Hi Sheila:
You will have to pinpoint what the engine is missing...
- Spark
- Fuel
- Compression

All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and fuel trigger. Both are very important and must be present for the engine to start. Fuel pressure is self explanatory. You just hook up the gage and see what the reading is. Fuel trigger is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should.

Compression tester, spark tester, fuel pressure gage and noid light are all accessible at your local auto store. All three tests play a very important part in diagnosing a no start condition. Be extremely careful when doing these tests.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

if anti theft module not communication with scanner or diagnostic hook up then your vehicle will probably not start till thats corrected and clicking sounds like relay from security system opening up and shutting down power for starting system

ecc and fuel pump relays good? when the engine is turning over, does the ck engine light go out? if not the PCM isnt getting a crank sensor signal. Power and grounds all ok at pcm?

try checking all the ground circuits comming out of the PCM. and its also not common for a ground driver in the PCM to fail on dodges. also i have seen crankshaft sensors short out and take out pcm communication. so i would start by unplugging any sensor that runs off the 5v supply until the pcm wil talk to the scanner. if you unplug a sensor and communication returns to scanner then replace the sensor. and dont forget to check for good power and ground at the data link conector and PCM

This is a bad PCM. Try to disconnect the security system first and if it still does not start then it is the PCM.