I have written previously about a 1993 E-150 custom van. It was running poorly, flashing code 51. I ended up changing the o2 sensor, the air charge temp sensor,the water temp sensor and none of those fixed the problem. I was then told to change the fuel pressure regulator and sure enough....it worked! The van ran great for about two weeks and then the fuel pump died.
I was finally able to get a fuel pump from Ford and replaced it....the van runs great, but no matter what I do....the air bag light keeps flashing code 51. I have just about had it with Ford. I am a certified mechanic and have been following a Ford service rep's advice all along on this vehicle. Putting it on the : computer has not reset the brain.....driving it after repairs has not reset the brain....leaving it sit with the battery doisconnected for a day has not reset the brain..........this customer is ready to kill me. The check engine light has stopped coming on but like I said...the air bag light is still flashing 51. What gives? I'm ready to take the bulb out or paint over it...hahahahaha.

 

I use black electrical tape to cover the bulb.

ECC 51; ECT sensor fault or circuit open. Engine coolant temp sensor.

IMO, a code scanner works great. $29 for the ECC model. also helps in clearing the cpu

 

I already replaced ALL the sensors and used the code scanner and the SUN Diagnostic computer...........Ford says it should be out......I'm about to put it out.......lol

 

check the wiring?

 

Yeah.....like I said....the van runs GREAT........the stupid light just will not stop.....

 

mrcards, Here's the info for code 51:
Normal Operation

NOTE: The air bag diagnostic monitor contains an internal thermal fuse that is not serviceable. The thermal fuse is controlled by a computer inside the air bag diagnostic monitor. The computer will blow the thermal fuse whenever a short on the deployment circuits occurs. The thermal fuse does not blow because of excessive current flowing through it. DO NOT attempt to jumper out the thermal fuse with a circuit breaker or any other type of fuse.

CAUTION: DO NOT install a new air bag diagnostic monitor until the short has been located and corrected. If a short to ground has not been located and corrected, then the short to ground is intermittent and is not present at this time. Installing a new air bag diagnostic monitor with an intermittent short in the system will result in blown air bag diagnostic monitors and repeat repairs.

The air bag diagnostic monitor measures the voltages at the diagnostic monitor connector pins. When certain air bag deployment wires are shorted to ground (heavy lines in the following schematic), the system may become susceptible to unwanted deployment of the air bag(s). The air bag diagnostic monitor senses a short to ground on any of these circuits and helps prevent unwanted air bag deployment by blowing the diagnostic monitor thermal fuse. Blowing this fuse removes all power (battery and backup power) from the air bag deployment circuits. While the short to ground exists, the air bag diagnostic monitor will flash code 13. If the short to ground is intermittent and temporarily corrects itself, the air bag diagnostic monitor will flash code 51.

NOTE: If the short to ground returns, the higher priority code 13 will flash instead of 51.

If the air bag indicator is flashing code 51 and a short to ground has not been serviced, this means that an intermittent short to ground exists in the supplemental air bag restraint system. The air bag diagnostic monitor should be replaced only after repairs to the intermittent short have been completed.

Some service tips for finding an intermittent short to ground follow.

1. Consult Ford On-line Automotive Service Information System (OASIS) Restraint Systems Service Code 104000 for up-to-date diagnostics and descriptions of wiring concern locations for the vehicle (VIN number) you are working on. OASIS is updated daily using concern descriptions from engineering and dealership service sources.
2. Inspect wiring and harnesses in areas where they pass through or are located next to metal components (i.e., engine compartment bulkhead, body sheet metal, component mounting brackets, etc).

After Air Bag Deployment

NOTE: Air bag diagnostic monitors can withstand several air bag deployments and do not need to be replaced after every deployment. Only replace the air bag diagnostic monitor if it is damaged.

Occasionally, immediately after an air bag deploys, the internal wiring of the driver side air bag module may become shorted to the metal housings of the driver side air bag module. This internal short is detected by the air bag diagnostic monitor as short to ground in the air bag deployment wiring. Since the air bag diagnostic monitor is still operating immediately after most deployments, the air bag diagnostic monitor will detect the shorted wiring and will flash code 13 and blow the internal thermal fuse. After the deployment, as the air bag cools off, the internal shorted wiring may correct itself, therefore the short to ground will no longer exist and the air bag diagnostic monitor will flash code 51. If a vehicle with a deployed air bag is flashing code 51, inspect and replace all the damaged areas of the vehicle with crushed wiring, sensors, etc. If no damage is found, assume that the deployed air bag was the cause for the intermittent short and replace the air bag diagnostic monitor when the new driver side air bag module is installed.

Code 51 Sequence of Events

1. Short to ground occurs on one or more of the circuits shown with heavy lines in the schematic.
2. The air bag diagnostic monitor recognizes the shorted wiring and flashes out a diagnostic trouble code 13 and sends a signal to the internal thermal fuse, causing it to blow.
3. The air bag diagnostic monitor will continue to flash code 13 while the short to ground is present. If the short to ground goes away, a diagnostic trouble code 51 appears.
4. The air bag diagnostic monitor only flashes a code 51 when the thermal fuse is blown and the short to ground is not present. Do not replace the air bag diagnostic monitor until the short to ground has been located and serviced. Consult OASIS for shorted wiring information.

 

learn something new everyday. Air bag codes are not ECC codes.

 

Not according to Ford...........On some earlier models......the check engine light comes on and then the air bag light flashes the code..........God help us.......hahahahahhah
Thanks High Top Van...I'll look into your info.......although the Ford rep said it's probably not that........so far he's proved that he doesn't know too much.

 

mrcards, Let us know how you make out.

 

Also thanks from me, Mr HighTopVan; although I do not really know what to do next as the information appears to be intended for Ford mechanics, who have access to OASIS and have schematics.

I have neither, only the Chilton book, and that is rather superficial, and even does not match with my van in many area's
As far as I can make out, my van is absolutely free of accidental damage, but has had a broken drivers door window from attempted break-in. (glass in the borrom of the door and minor dent in upperwindowframe) so the airbag should not be deployed.
So there has been an intermitted short.......without schematics and the location of components there is not much I could do.
It is of course nonsense that a thermal fuse can not be replaced, they are availble in all sorts of values at a few cents...
So, where is the airbag diagnostic monitor, and where is the likely non-existing, previous short? In the steering wheel?
Believe that the black vinyl tape is going to be the solution for me......
Cor

 

I just returned today after a 3000 mile trip with my van. It ran great but I have not been able to trace the problem with the air bag light as of yet. Several mega Ford dealers from Pa to Texas have no clue either. I talked to a midwestern Ford rep and he suggested replacing the air bag assembly.........The only thing that I cannot understand(after being a trained mechanic for many years on BMW, SAAB, Peugeot and GM) is where do they get these supposedly intelligent factory service reps for the American car companies? Ford still claims that the air bag light is flashing the code for the ECC. Since I have a wife and kids who drive the van...I'd like the air bag to work. Oh and in case any one is wondering....the ck eng light and air bag light came on at the same time a few weeks ago and the sensors that I replaced according to the Ford service manual for code 51 fixed the running problems. The ck engine light went out....but not the air bag light.........

 

The ford reps you have been talking to must be totally stupid, the ECC (or engine control computer) and the air bag diagnotstic module are two separate computers, I think it's just coincidence that they came on at the same time... There is a short in the wires going to the air bag from the diagnostic module (as stated by a previous post of the tech manual), you need to find that short, fix it, and then replace the module, that should clear the air bag light.

 

Like pfogle said the 2 systems use 2 seperate modules. The EEC (Electronic Engine Control) system should have nothing to do with the air bag system and I dont think there were ever tied together.

The shop manual says........
While the short to ground exists, the air bag diagnostic monitor will flash code 13. If the short to ground is intermittent and temporarily corrects itself, the air bag diagnostic monitor will flash code 51.

NOTE: If the short to ground returns, the higher priority code 13 will flash instead of 51.

I've had a few code 51's and couldn't find a problem. Replacing the Air Bag Diagnsotic Monitor (air bag module) cured them. If you dont want to buy a new one just in case it happens again, maybe see if you can find a used one to try.