Monday, July 25, 2011

Fuel pump relay and cooling fan relay troubleshooting on 1997 ford thunderbird

Fuel pump relay and cooling fan relay

Ford Fuel pump relay and Ford Cooling Fan relay troubleshooting is as follows:------

Here is the fuse location (fuse 13) and also the constant control relay module location.The Ford fuel pump relay is located in this module.

And later also go through the Fan relay possibilities after fuel pump relay.

Ford Thunderbird Fuse box And Relay


Ford Underhood Engine Component location


The relay is located in the engine compartment in a relay box. It is a long narrow black plastic box with removable lid, and sits next to the radiator overflow/fill reservoir.

If your cooling fan is running(this is the default,if you disconnected the PCM and then turn the key to the run position the cooling fan will run) and your OBD2 scan tool is not linking up your PCM is not powering up.

When it is acting up check and see if you have power on the red wires on pin 71 and 97 at the PCM.This gets its power from the PCM relay on the ICRM(intergrated control relay module).

Here is a copy of the wiring schematic to help you.
Ford Thunderbird PCM to cooling fan relay wiring
Here is the connector at the PCM


The relay control module is the one located on the radiator support that houses the relays for the PCM,Fuel Pump,AC,Cooling fans.

Here is a pic of the connector at the relay module.
Now how this works is looking at the wiring schematic I sent you the red/light wire on the right at pin 13 is the power feed for the coil side of the PCM relay,the black wire on pin 15 is the ground for the coil side of the relay. When power and ground are applied to the coil side of the relay,this creates a magnetic field which will pull the switch side of the relay closed.Looking at the left side of the schematic the switch side is the yellow wire on pin 8 and 10 which gets power from fuse 15L. when the switch is pulled closed power then can flow from the yellow wire to the red wire on pin 24 which feeds pins 71/97 of the PCM.
Now when it acts up if you have power at pins 71/97 then the problem is the PCM or one of the grounds to the PCM(look at the connector pic for which wires are ground).
If you do not have power to these 2 pins then your problem is either the wiring from the relay module to the PCM or the relay module itself.Most likely I would suspect the relay is sticking how ever a corroded wire or connection could also cause it.

The PCM is located behind the right kick panel. Here is a pic of the location


Yes, I've ordered a IRCM Intergated Relay Control Module yesterday, because I've been told by a Ford Mech. (retired) that these fail from the High Heat. It has been 95+ this last week, and I broke down and used my AC. Never use the AC much.
I reseated the gound cable from the Battery to the Radiator Support, removed and reseated the Connector on the IRCM that's mounted on the Rad. Sup. behind the Air Filter Box, reseated the Connectors by the ECM behind Pass. kick panel, Loosened ( didn't completley remove) the ECM Connector and retightened, reseated the Ground Cable that's next to the ECM. Replace the Relay in the Power Dist. Box for the Fuel Pump.
After all that the car started hard, and the Rad. Fan didn't run as it was before. I made it to work fine. At lunch it didn't run the fan, and wouldn't start, finely after several tries it started as normal. Started 4+ times after that during the hour. When I got ready to go home, it started hard, but did start. It was only 90 out that day.
Today went out to start it, 73 outside and cool. I turned on the ignition and heard the Rad. Fan runnning, Fuel Pump run for about 3 seconds. Cranks over never tried to fire.
On/ OFF the Key several times and still nothing.
QUESTION FOR TODAY: About the Grounds for the IRCM and the ECM. I know that the gounding of these items, especially the ECM are very important. Can you tell me how to check these and there LOCATIONS. Also can I use a 12V light probe to check the ECM for 12V? I do have a Fluke, light is easier.
To check the Voltages at the ECM, can I drop it down without causing any problem with ESD? Does it need to be grounded when I let it hang?


You can just let the PCM hang down and check the wiring that way,the PCM does not have to be grounded.
Yes you can use a test light instead of a voltmeter.
You can check the grounds at the IRCM and PCM with your test light also just hook it to a power source and test the grounds that way. You should be able to use the connector view I sent you for the grounds. If you have one that is bad let me know which one it is and I will get you the location.

Are the Ground bus flat? About 1 1/2" X 2 1/2" X 1/4" thick? They are Clear white and have about 6 wires attached to each, and nothing else, expect the mounting screws. Because I'm seeing them under the hood and several places else.
As you have stated there are several grounds.But first make sure when the vehicle acts up that you have power on pins 71 and 97. You need to try and pin-point a starting point here.Just to give you an example the wiring schematics are 18 pages long for just the grounds. I can not upload all of this to you. If you can pin point the area I can upload that.
Start at the 2 power pins first lets make sure when the vehicle acts up that these are powering up. You can leave the PCM hanging down so you can easily access it and have your test light in the vehicle and the next time when you turn the key on and hear the cooling fan running check these 2 pins.
As I stated earlier this is the default for no power to the PCM,if you were to unplug the PCM then turn the key on the cooling fan will run.
If you want to go ahead and check the grounds for right now check them right at the PCM connector with the PCM disconnected and make sure you have them all. If you do not then post back which one you do not have and I will upload that page and location for you.
I'm working on this tonight and tomorrow, trying to get as much info as possible before I start tearing it apart. I want to cover as much as possible so I don't have to spend days on line.
I am going to check the 71 and 97 for voltage at the PCM first as stated. Then all the grounds, in and around the PCM, IRCM, etc. I just want to be able to work on it without the lack of all steps needed to complete this troubleshooting and repair.

I studied the wiring schematics and there are really only 3 ground locations for the PCM and 1 for the ICRM that you really need to check.
The PCM ground are G200,G202,and G104 and the ICRM is G139.Here are pics of their locations,I have circled them in the pics.

For Further Troubleshooting Go Through Part 2 Of This Guide.