Would a bad Relay Control Module prevent starting?

[EL SHO]

Simple question guys... would a bad relay control module, part # F1DF-12B577-AA, cause the Taurus not to start? What does this box really do?

More in specific, the starter will not spin and the engine will not crank but I know the starter is good.

Besides the Neutral Safety Switch, that I've also changed, does this module when goes bad prevent the current from flowing to the starter or to other things as well along with the starter?

 

[projectSHO89]

A faulty CCRM won't cause a "No crank" symptom on a 94 ATX.

For functional details of the CCRM, see this permanent post: http://www.shoforum.com/showthread.php?t=75065

The starter circuit on a 94 ATX is pretty simple: Ignition switch to the MLPS to the starter motor. Nothing else to it except the power supply to the ignition switch.

 

[EL SHO]

A faulty CCRM won't cause a "No crank" symptom on a 94 ATX.

For functional details of the CCRM, see this permanent post: http://www.shoforum.com/showthread.php?t=75065

The starter circuit on a 94 ATX is pretty simple: Ignition switch to the MLPS to the starter motor. Nothing else to it except the power supply to the ignition switch.

Thanks a lot man!

Then seems I have a lot more to research as to why my car won't start even with a new NSS.
I took my car to the shop since lately I haven't had the time to really investigate and work on it, I bought the NSS to get it installed and my mechanic says that didn't help and that it was the CCRM. I found one to test with but I didn't really know what is the purpose of this module.

 

[Off Road SHO]

El,

Have you done any work on the SHO recently? Did it just not start one day so you had it towed to a mechanic? How do you know the starter is good, did you remove it to test it?

Tom

 

[rubydist]

you have the potential of:
ignition switch bad
fuseable link bad (ignition circuit)
starter solenoid bad
starter bad
wiring to starter bad

 

[EL SHO]

El,

Have you done any work on the SHO recently? Did it just not start one day so you had it towed to a mechanic? How do you know the starter is good, did you remove it to test it?

Tom

I just went to the grocery store one day and when comming back it would not crank, everything else work with the key on ON, so I had it towed. It had happened before but moving the lever to Neutral or Neutral and again to Park will make it start, but not this time.

Work done recently done to the car was changing the battery as the old one was cracked and would not start the car anymore, but that day all lights were really dim, even the dash lights.

I know the starter is good cause the mechanic tested by directly wiring the starter to the ingnition wire (white with pink) and the car did start, but by doing that it was throwing out codes that it couldn't detect if the car was in PARK, with that I assumed that the NSS had gone bad so I went to get one and gave it to my mechanic to install it. He mentioned that even with the NSS the car didn't start and he believed it was the CCRM, which I got an extra one to test with now.

If the NSS is new, and the car will start by wiring the starter directly to the white-pink strpe wire in the steering column, could there be a chance that what is wrong is the actual start switch box under the dash?

I remember I had an issue with my Mustang and a Thunderbird in which a plastic lever that goes from the key and pushes the main switch to the ON position and then to Start, will break and I won't be able to switch the cars off. Could that main switch box cause this type of issue? I would guess the SHO also has this main switch box.

 

[rubydist]

yes, a bad ignition switch is the first item I listed in my last post of possible culprits. this is not uncommon in the Taurus.

you also have the possibility that the neutral switch is either bad or not aligned properly.

 

[Phoenix]

Just for the record , no crank or no start?

2 diff things.

If its really a no crank , the CCRM has nothing to do with that.

no crank = Neutral switch , batt wires + and - , starter solenoid , Really bad ground from the engine to the body.

And maybe the starter/flywheel gears (if the starter turns but not the engine).

 

[EL SHO]

Just for the record , no crank or no start?

2 diff things.

If its really a no crank , the CCRM has nothing to do with that.

no crank = Neutral switch , batt wires + and - , starter solenoid , Really bad ground from the engine to the body.

And maybe the starter/flywheel gears (if the starter turns but not the engine).

That would be no crank only, the car does start if the started is bridged directly.
Maybe, like rubydist says, the new NSS is not aligned properly or the ignition switch is toast, will check on that this afternoon along with any grounds.

I might as well then return the CCRM I bought before installing it.

 

[Shovert]

Mechanic should be able go thru wiring diagram and find problem. One for the Taurus I assume same as SHO. Easiest one to get without going thru a large PDF file.
http://www.autozone.com/autozone/repairguides/WIRING-DIAGRAMS/WIRING-DIAGRAMS/_/P-0900c152802798c9
Maurice
Edit of course it is the last one.

 

[EL SHO]

Mechanic should be able go thru wiring diagram and find problem. One for the Taurus I assume same as SHO. Easiest one to get without going thru a large PDF file.
http://www.autozone.com/autozone/repairguides/WIRING-DIAGRAMS/WIRING-DIAGRAMS/_/P-0900c152802798c9
Maurice
Edit of course it is the last one.

whoa!

Thanks a lot for the diagrams! The ignition/starting diagram is not that complicated: Battery, Ignition Switch, NSS, Starter solenoid and then the starter.

If the NSS and/or Ignition Switch are bypassed, what problems would the car have? (because that was what my mechanic suggested, to run an independent circuit for the starter... I guess he thought that was more simple than to find the real issue )

 

[Shovert]

It is a fairly simple circuit. Now my thought, Ok to bypass and test something. Leave it that way. No way. I personnelly hate butchered wiring. I have a MG Midget and seem like that is first thing people want to do when can't read a diagram or won't take the effort. Maurice
Ok This is the big PDF I was refering to. It is a Russian site. Maurice
http://taurus-club.ru/manuals/Ford_Taurus_1994_wiring.pdf

 

[rubydist]

you cannot just bypass the neutral start switch - the pcm has a rev limiter at 4000 when in neutral, so you also have to complete the circuit to tell the pcm that its in gear, or else you will never get over 4000 rpm.

there are descriptions of what needs to be done to accomplish this in a couple of threads on the forum that are about converting from atx to mtx.

 

[Off Road SHO]

The PCM relies on resistance values from the MLPS switch that is located on top of the transmission. Pin 46 of the PCM feeds I think 5 volts to the MLPS switch on a grey w/red stripe wire. As the lever is moved from 1st through Park, ever increasing amounts of resistance is added to the line, starting with 78-95 ohms in 1st to 3770-4607 ohms in Park. The signal goes back to the PCM on a Light Blue w/yellow wire to pin 30.

Again, I am not sure which direction the circuit read or whether the PCM is monitoring resistance between the two pins or voltage.

Tom

 

[Shovert]

There are several circuits in the MLPS switch.
Start circuit from ignition swicth goes thru white/pink and out the red/light blue to the starter solinoid also goes to the ignition control module also.
Like you said the pin 46 thru the MLPS varying resistance back to pin 30. In drive 400 ohms. Removes the 4k rpm limit.
http://www.speedfreaksgarage.com/jeff/ATXtoMTX.pdf
Info on the switch here.
http://www.shoforum.com/showthread.php?t=109308&highlight=mlp
MLPS switch from 3.2
http://i177.photobucket.com/albums/w224/mgman75/93 mustang converiable/temporarypic001.jpg
Thanks Maurice