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1995 Taurus won't start, won't communicate, cooling fan stays on.
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wayne77
Novice
Jun 23, 2010, 9:02 PM
Post #1 of 2
(2136 views)
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1995 Taurus won't start, won't communicate, cooling fan stays on.
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Dear Technician,
RE: 1995 Ford Taurus SE 3.0L with 150,000 miles.
This vehicle won't start and won't communicate with the Snap-on MT2500 Scanner. The cooling fan comes on low when the key is turned on. Upon disconnecting the PCM, the cooling fan still comes on when the key is on.
We replaced the original-1st Constant Control Relay Module (CCRM) with a used-2nd unit and then with a remanufactured-3rd unit. No improvement.
I have removed the negative battery cable ground connectors and soldered the ground wires directly together.
I have exposed/unwrapped the engine wire harness from the Constant Control Relay Module to the Powertrain Control Module. This revealed the section along the back of the engine where temperatures were highest, and which caused the wire insulation to fuse one to the other. In separating these wires I observed five wires had copper strands exposed. It is difficult to determine if copper was touching copper, because some of the insulation tore upon separation. However, I taped the five exposed copper wires to continue analysis.
I have tested the Data Link Connector (DLC) and it tested normal.
The engine has good spark and fuel pressure.
I have traced and tested the PCM ground wires and power wire, with satisfactory results.
When I stick the Tan/Orange wire at CCRM pin 14 (circuit 197) with a grounded test light it draws enough current from the circuit to cause the cooling fan to stop running.
My presumption is that there is a keyed circuit using the cooling fan circuit as a ground, or that the PCM is defective due to possible wires previously touching in the harness.
Is there an outside test for a non-communicating PCM to determine if it is defective?
Is the constant cooling fan on condition a known symptom of a malfunctioning PCM?
Your input will be greatly appreciated.
I have read previous Ford wiring analysis strings that did not have the results posted, and I will post the followup results when this problem is repaired.
Sincerely,
Wayne
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Sidom
Veteran
/ Moderator
Jun 24, 2010, 1:38 PM
Post #2 of 2
(2107 views)
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Re: 1995 Taurus won't start, won't communicate, cooling fan stays on.
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If possible, try another scanner to make sure there isn't something going on with the scanner.....If you have a different data cable for your brick, try that,,,,there was some issues with the cables..
Sounds like you are on the right track, definitely fix the wires you found with bare spots............
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