cooling fans

[93shoboy]

I replaced my radiator last night which took care of the coolant leak and the car seems to cool better, but i noticed that the cooling fan wasn't turning on, it usually kicked in when the needle was around the O or R on the gauge, but it got up past the N and no fan. Is there a sensor i need to check and if so where is it? my dad and I looked for it and found nothing, and the Chilton's manual is all but worthless for the SHO. Any ideas as to what can cause this and/or suggestions on how to fix it would be greatly appreciated.

 

[Slo-Sho]

The sensor for the dash gauge is located in a way that an air pocket can form around it. Your cooling system just needs to be bled.

 

[DHMag]

once the system is properly purged and the fan still doesnt come on. switch on your A/C and the fan should come on automatically. if not, youll find out that the fan motor needs repair. also worthwhile of doing is changing the thermostat, its simple and cheap.

 

[91SHO-Plus]

I too am having the same problem. I hook the fan straight to the battery terminals and the motor does work fine and spins ok. But when I hook it back up to the wire harness and relay box, it refuses to come on and the car will overheat. I have already changed the thermostat too. I have changed out the control box with several others from a local salvage yard, and still nothing? Is there a relay or fuse under the dash that I might need to check? I dont have an owners manual so I have no idea whats under there in the fuse panel?

Jon 91 SHO

 

[SHOtimer]

You all might have a bad ECT (Engine Coolant Temperature) sensor. It has nothing to do with the dash gauge. Looking straight at the thermostat it is directly to the right, (the side closest to the fire wall). It is screwed into the metal portion of one of the lines going to the heater core. It has a normal 2 wire wire harness going into it. It is a very simple replacement, unscrew out, rescrew new one in. What it does is lets the computer monitor the temperature of the engine, which helps it decide what mixture to run the engine at AND when it should turn the fan on and how long. This little 7$ sensor could be the root of your problem, it is cheap and easy enough to try. Hope this helps,
Doug

 

[SHOZ123]

Sounds like the relay in the CCR/ICRM is bad. You can jury rig a seperate relay for a few bucks or get a new module.

 

[projectSHO89]

Jon,

Here's how to really troubleshoot it, not just swap parts on hunches or based on prior experiences... These instructions apply to GEN 1 systems.

Tool required:

You will need a voltmeter with the negative lead attached to ground. Proceed to the next step only if test passes or unless instructed to do so.

1) Verify supply voltages to IRCM. You should have Vbat on IRCM pins 1 (BLK/OR) and 2 (BLK/OR). If no voltage, check fusible link J (18 ga BRN).

2) Momentarily ground the EDF control line on pin 14 (TAN/OR) at the IRCM. The relay in the module should energize and the fan should come on. Is so, go to Step 3.

2a) Connect meter to IRCM pins 3 or 4 (should be either BRN/YEL or DK BLU) and repeat test 2. If you measure Vbat, there is an open wire between the IRCM and the fan or the fan's ground circuit is open. If you do not measure Vbat, the relay in the IRCM is defective.

3) If you reached this point, the fan and the relay module are okay. The problem is that either the computer is not turning the fan on, or the signal from the computer has been interrupted due to a wiring harness fault.

The primary input to the computer that determines the fan operation is the ECT (Engine Coolant Temperature) Sensor. It is mounted exactly as SHOTimer said.

The sensor and it's wiring can be tested.

1) Disconnect the connector. Measure across the sensor terminals. The measured value will depend on the temperature sensor.

Temp is in C, resistance is Kohms:

10 58.75
20 37.30
30 24.27
40 16.15
50 10.97
60 7.60
70 5.37
80 3.84
90 2.80
100 2.07
110 1.55
120 1.18

All values may vary by +/- 15%. Values below 10 C are not given but may be estimated by extrapolation.

If the sensor tested okay, connect the meter between the connector that goes to the sensor and turn the ignition swith to RUN (+ lead to BK/W, - lead to LG/Y). You should measure 5.0 V. If not, troubleshoot Vref(erence) circuit.

If the sensor tests good and Vref is present, the problem is either a fault in the wiring harness or the computer is the problem.

In many years of repairing electronics, I have found that disconnecting, inspecting for visible corrosion, and reinstalling connectors will take care of many problems due to mild corrosion in the connector. You might want to try this on the ECT sensor, the IRCM module, and the EEC-IV module connectors. Disconnect the battery first!

Steve

 

[greenmachine]

Thanks Steve, I needed that info too.

 

[rangerj]

Steve,

I am so glad you posted this reply. Several weeks ago SHOTHANG posed the question "what do you do with the codes". Your response is the answer, that is, you do the "diagnostics". The code is just the clue as to what the problem might be.

In the case of a temperature sensor, it may not "code". I had one recently that produced an amount of resistance that was within the range that the computer was programed to expect. The problem was that the sensor's resistance would not vary with temperature.

Like you, I frequently find poor connections due to corrosion or a loss of tension in the female side of the connector (that is the female side is not tight enough). (Don't go there guys)

Steve, is there a web site that has the specific series of tests and proceedures for each sensor in the SHO?

What about test equipment? I use a multi-meter that can measure voltage, ohms resistance, continuity, amperage, including mili-amps. Sears and Radio Shak sell a good unit for about $40 to $50. A test probe, a screwdriver with a light in it and a ground wire attached, is also very useful for testing circuits.

Steve, or anybody else, want to add anything?
Thanks again Steve. rangerj

 

[projectSHO89]

Rangerj,

That procedure was derived from the Probst EEC-IV manual, the 89 EVTM, and my own analysis thrown in.

The Probst book does have specific tests for many of the sensors and controls used on all EEC-IV engines. I only got this copy about a week or so ago, so I'm just starting to learn what all is included. It will be worth far more than the $15 I gave for it to a mailing list member. I am not aware of any web site that has the information you requested in any publicly accessable area.

FYI, the title is "Ford Fuel Injection & Electronic Engine Control" by Charles O. Probst, ISBN #0-8376-0301-3 and is available new from Amazon.com for under $21. See http://www.amazon.com/exec/obidos/ASIN/0837603013/qid%3D1042569926/sr%3D11-1/ref%3Dsr%5F11%5F1/104-9756745-3963148

I use an inexpensive auto-ranging meter from RatShak for all my work, whether hobby or professionally. It cost about $35 and does almost everything I need except measure very large currents (over 10 Amps). Harbor Freight sells an inexpensive DMM that costs less than $10, but I wouldn't know how long it will last or how accurate it will be tomorrow. Sears Hardware sells a perfectly adequate DMM for $20. As far as test lights, if you are testing digitals signals, do not use one with an incandescent bulb, get one with an LED.

Hope this helps.

Wish this forum used stickies to keep useful posts at the top, an FAQ forum for the FAQ posts, or that the SEARCH feature worked right.

Steve

 

[rangerj]

Steve,

I also have a number of auxilary manuals relative to testing automotive electronics (so called "drive-ability" manuals). I do not have the Ford book you mentioned though. It will be ordered tonight.

I agree with you, we need an FAQ section. Let US think about putting together a list of the SHO sensors and the diagagnostic steps to determine if the sensor is bad, or the problem lies elsewhere.

A description of how all the sensors are interrelated, and what the do, why they do it, and how they do it, might also help. Every time I think about doing this I stop and think, "will they read it"?

Anyway, give it some thought. We could divide up the sensors and put together a set of test proceedures for each of them.

The following book may be of interest to you. "Tuning Up Autos and Trucks, A Guidebook of Solutions for Testing, Evaluating, and Analyizing, Computer Controlled Vehicles" by
Milton Webb. $49.95 (450 pages)

Milt, the Instructor
8737 Lodestone Circle
Elk Grove, CA 95624

Ph. 916-685-4527, e-mail [email protected]

I just got mine. So far, so good. Tomorrow I will go and get a test probe with an LED light! Thanks again, rangerj

 

[projectSHO89]

If nothing else, a "Hall of Fame" section for the posts with always useful posts that get referred to frequently, like Scott's 60K information, timing belt installation photos, parts sources and numbers and all the other common stuff.

Steve