PDA

View Full Version : Died while driving won't start


francij1
April 27th, 2012, 05:55
1993 Sport 4.0l manual, driving along 40mph in 4th engine dies like you shut the key off, tow it home and start searching these awesome forums! So far i have checked for 8 volts on the orange wire to CPS and ran ohm's test to pins B and C and have infinite resistence, swapped relays for ASD with A/C relay, checked all fuses, verified 12 volts to coil lead with key in on position, but while cranking i lose the 12 volts at the coil lead indicating the ASD is killing the voltage i assume. So my question is if i lose that voltage to coil while cranking could it still be the CPS even though it tests ok? What other signals does the ASD need to see besides the CPS that may be causing my problem?

Thanks,

8Mud
April 27th, 2012, 08:04
I've never had the problem myself, but people say a failed sync/cam position sensor can cause this in non Renix models.

I had my 96 do this, turned out to be the factory/dealer installed anti theft module. I jumped it and threw it away.:gee:

birchlakeXJ
April 27th, 2012, 10:32
Spark: 12 volts from ignition switch to the ASD relay; when the key is first turned on the PCM provides a ground to the ASD relay to energize it, then the ASD relay passes 12 volts to the coil primary side. If no crank sensor signal is generated after a couple of seconds the PCM cuts the ground to the ASD relay (and fuel pump relay too) and that cuts power to the coil (and fuel pump). Key to START and once again the PCM energizes the ASD relay. Now, a critical element is the crank sensor--no signal from the crank sensor and the PCM won't trigger the coil to provide spark.

francij1
April 28th, 2012, 07:13
Update, so my assumption was completely wrong, my non-analog volt meter was not sensing the voltage change occuring at the coil lead while cranking. So i short the wire from the output of the coil to the block and i have to be literally a millimeter away before i see the faintest of spark so i short from the post on the coil to the block with a screwdriver and again it wont jump anything but the smallest gap and very faint spark. So i pull the coil and head the the local discount auto chain for a BorgWarner coil and test the differences between the two, across the pins I have .5 ohms old and on new one 1.2 and pin to output post old has 6.5k new has 9.8k ohms so my lesson is always second guess yourself when chasing electrical demons and when people suggest testing things effing do it! Thanks ya'll

jmeti000
April 28th, 2012, 10:43
Mine had the same problem...would randomly die while driving, but because its a manual and would be in gear it would start up again. A friend of mine who happens to be a mechanic said hes seen this alot with ford cars and its always the ingnition module. On that I decided to slap in a new one as well as a coil (since its right there and pretty inexpensive)...havent had the problem since. Apparently the ingnition module can suffer from thermal failure, which in turn cuts off the spark/power and the engine will then just turn off...or something along those lines.