2000 Vic Coolant fail safe mode

[way2old]

Well we got one that is kicking us pretty badly. 2000 Crown Vic P71. When it feels like it, the coolant temperature light will come on and the engine will just cut out like the ignition is shut off. We have determined that it is placing itself in fail safe coolant mode. However, the coolant temp and cylinder head temp are working properly. All scan data looks normal. Nothing out of the ordinary. Vehicle came in for small fire under the vehicle and we determined it started from something on top of converter on drivers side. All sensors work normally and the PIDs are correct. Fuel pressure is dead on the money, new plugs. The only thing that comes up is the OLDRV. I am assuming that is something that controls open loop fuel in the vehicle. I have never seen it and can't find acronym for it. Soooooo, if anyone has any bright suggestions, or just suggestions, they are more than welcome. Next step is to check wiring to see if anything is out of whack there. Thanks all.

UPDATE: just left vehicle. Did 3 almost wide open throttle stomps in the bay. Check engine light came on and then car died. Lost all communication with PCM while this occured. Unplugged power relay and plugged it back in.--had power. Stomped it again--check engine light came on, no power to scan tool no start. Turn key off and started right up next try. Somewhere there is a gremlin that is laughing real loud. Keep ya informed. At least we have it narrowed down to electrical. Oh, also no codes.

[way2old]

If anyone is interested, we found the problem. You guys that work on them all the time know what I am talking about. It was circuit 915, pink and light blue wire going to the PCM and DLC.(Multiplex wiring system) Ford's famous wiring harness under the battery had corroded the wire where there were only a couple of strands left and the torque of the motor was causing it to lose power. only got about 14 hours in this one. Glad we are not on flat rate.

[radioman2002]

While I havn't had a problem as perplexing as yours, I was very supprised to see that my 199CVPI had such a thing. My coolant must have run low, because while responding to a call, the car basically shut down after a full bore throttle getting on the interstate. As expected the CEL came on, and the car ran rather poorly, so after getting it home and running the code, which came back as insufficient coolant left bank. I had never heard of such a thing up till then, but was very appreciative that it did exist, for not knowing how much damage I might of caused, if it didn't. I was aware of the thermal sensor located on the back of the heads on the older 96-97 CVPI that melted if the car ran over 210 F, but was not aware of an actuall sensor that would shut the car down into a limpin mode.