Questions and Answers

Ford Taurus Starts, Warms Up, Dies Q. I have a 1989 Ford Taurus GL, 3.0 liter engine, automatic transmission, P/S, A/C cruise control and 167,000 miles. When cold, it starts and runs fine, but after warming up for 15 to 20 minutes, it stalls and will not restart until it has cooled for an hour or more. It shows a trouble code 14 Loss of PIP signal.

I know this can be the TFI module or the PIP in the distributor. I have found several posts about a bad PIP causing a TFI to go bad and about how both should be replaced at the same time, but others where somebody replaced both and still had the same problem.

Before I put another $100.00+ into a new distributor and module, what else should I check? Do I need to replace both?

A. A code 14 indicates two successive erratic Ignition Pickup (PIP) pulses occurred, resulting in a possible engine miss or stall. This can be caused by a loose electrical connector, or bad secondary ignition components, distributor cap, rotor, ignition wires or spark plugs.

Before you attempt to troubleshoot anything else, we need to be sure these items have been checked or replaced as needed. If they are good, then we can go looking elsewhere for the problem.

The Profile Ignition Pickup (PIP) signal is created in the Hall Effect and Stator assembly and indicates crankshaft position and engine RPM. The PIP signal is fed to both the TFI module and the ECA. The Hall Effect device is made up of a voltage regulator, a Hall voltage generator, Darlington amplifier, Schmitt trigger, and an open collector output stage integrated in a single monolithic silicon chip. A signal is produced when a ferrous material is passed through the opening and the flux lines decrease.

The Hall generator (Hall device) sends a sine wave signal to the Darlington amplifier. The Darlington amplifier inverts the signal. When the signal is low the output is high. When the signal is high the output is low. This output then goes to the Schmitt trigger. The Schmitt trigger shapes the signal into a square wave (digital high) signal.

The output signal to the Darlington amplifier is high when the window (on the armature) allows the magnetic field to reach the Hall device (switch off). When the TAB shunts the magnetic field (closes) away from the Hall device the signal is low to the Darlington amplifier (switch on).

In other words when one of the windows or openings is in the gap between the Hall device and the permanent magnet, the field stays strong and the voltage is high since the magnetic path is complete from the magnet, through the Hall device, and back to the magnet. In this case the switch is off and the Hall Effect does not send a signal.

When the TAB enters the gap, the armature cuts off the magnetic path to the Hall device and its voltage drops. In this case the switch is on and the Hall Effect device sends a signal. The signal is switched On and Off as long as the armature is rotating (distributor is turning) and opening and closing the magnetic path.

This is the signal used by the ECA to interpret crankshaft position and engine RPM. The signal can also be used by the TFI module if the SPOUT signal from the ECA is lost.

The TFI IV ignition module has six connector pins at the wiring harness that supplies the following signals:

• Run
• Crank (start)
• Tach (coil)
• PIP (crankshaft position to ECA)
• Spark output (SPOUT from ECA)
• Internal ground from the ECA to the distributor

The TFI IV module supplies the spark to the distributor through the ignition coil and calculates the duration. It receives its control signal from the ECA (SPOUT).

There is a pinpoint test procedure to determine where the problem is. Personally, going by your description of the symptoms, I feel the problem is very likely the TFI module. They typically go bad when they get hot and will start working again when they cool off.

I would include the diagnostic procedure here, but it is a bit to involved. You can find it in the Mitchells or Motors manuals in the Reference section of the Public Library.