P1670 not start

purpleheart350 · Mar 2, 2013

I just filled the Ex up 2 days ago ($125) last night went to get dinner, hoped out left the truck running. Came back 1 min later theft light was flashing so I turned it off and tried to restart now I am getting the theft code (can't remember the code #) and P1670 EF signal not detected. Fuel gauge says empty, over head says 0 miles til empty, tach doesn't move, fuses seem good. I moved fuses around (blower to PCM) and moved IDM fuse and still nothing. I have read about swapping idms and seeing if that works. But if doesn't then what is next. I also read to do some other test but no where explained. One of them also said to do a koeo but how is that possible if the truck won't start.

Powerstroke Cowboy · Mar 2, 2013

Just some info I picked up. not sure if it will help you though..

DTC P1668 and P1670 indicates that a communication error has occurred between the PCM and the IDM.
Possible causes:
Open fuse
IDM relay
Open or shorted IDM enable circuit
Open/short in EF circuit
Open/short in FDCS circuit
IDM powering circuits
PCM
Check for other codes.
Key on, engine off.
Perform KOEO On-Demand Self Test and retrieve Continuous DTCs.

purpleheart350 · Mar 2, 2013

Powerstroke Cowboy said:
Just some info I picked up. not sure if it will help you though..

DTC P1668 and P1670 indicates that a communication error has occurred between the PCM and the IDM.
Possible causes:
Open fuse
IDM relay
Open or shorted IDM enable circuit
Open/short in EF circuit
Open/short in FDCS circuit
IDM powering circuits
PCM
Check for other codes.
Key on, engine off.
Perform KOEO On-Demand Self Test and retrieve Continuous DTCs.

How is that possible when truck won't start. I read all that already but what are the circuits, where are they located, fuses check out ok.....

Powerstroke Cowboy · Mar 2, 2013

I really cant help you there.. That test needs to be done running SO i guess that is out of the question.. Your IDM might be bad...

purpleheart350 · Mar 2, 2013

Check engine light doesn't come on either

Powerstroke Cowboy · Mar 2, 2013

Does the pickup crank over?? Wish i was closer I have 6 IDMs just sitting around

Arisley · Mar 2, 2013

purpleheart350 said:
How is that possible when truck won't start. I read all that already but what are the circuits, where are they located, fuses check out ok.....

KOEO meens Key On Engine Off KOER mean Key On Engine Running

purpleheart350 said:
Check engine light doesn't come on either

This could mean that your PCM is not getting power. I know you said all fuses are good, but did you check the under hood fuses and the fuses under the steering wheel?

Also it could be the PCM relay.

Powerstroke Cowboy · Mar 2, 2013

Arisley said:
KOEO meens Key On Engine Off KOER mean Key On Engine Running.

:doh: I forgot!!! LOL. Thanks for the clarification!!

purpleheart350 · Mar 2, 2013

Yea I swapped fuses under the hood and dash even swapped diodes to see if that helped. Just thinking about going and getting all new fuses to swap and have spares

purpleheart350 · Mar 2, 2013

Going to swap idms if that works then getting swamps IDM if not could the PCM be fried

Arisley · Mar 2, 2013

Just check the fuses with a meter. They are either good or bad. Don't forget relays. You can swap the blower motor relay with the PCM relay to see if that is the issue. I keep a couple spare relays in the truck. The same relay is used just about everywhere, not only by Ford, but by every manufacturer.

purpleheart350 · Mar 2, 2013

Can anyone think of anything else

Powerstroke Cowboy · Mar 2, 2013

Does your tack move when cranking?? I know this has nothing to do with the code.
Did you check the HPOP psi when cranking?? Does any of the relay under the hood click over and over when you turn the key on??

ghohouston · Mar 2, 2013

Tach doesnt HAVE to move, and on what i believe arisley said was 2002 and 2003 trucks, it wont move until started

Powerstroke Cowboy · Mar 2, 2013

It a 2001... And the one we had moved when cranking...

ghohouston · Mar 2, 2013

I believe the 2001 and older SHOULD have tach movement, and is related to the cps, which is why people always ask with a no start if there is tach movement, but does not ensure cps failure

Powerstroke Cowboy · Mar 2, 2013

I have one that shows 250 to 300 RPMs when cranking

purpleheart350 · Mar 2, 2013

No tach movement, no wts light, swapped IDM and still no start. Have to wait til Monday to see what codes come back. Could I buy/swap PCM and see if that works. Other than that off to ford rape house.