Is It the Remote Starter:

Dear Roy, The vehicle is a 2003 Ford F-150 Supercrew pickup truck, VIN 1FTRW08LX3KD22559, with a 5.4L engine and and a 4R70W transmission.

I installed a remote starter, a Compustar 2 WAM-S. All connections are soldered and sealed with shrink-tubing. The vehicle starts and runs for about 15 seconds, then shuts off. It will restart and shut off again three times, then it stops trying.

Sometimes it will start and stay running, leading me to believe it is a problem with the unit as it does work properly on occasion. I am using the alternator as a signal. In the manual it says the parking lights will flash if there is a problem, but they don't.

Have you heard of this or have any ideas?

Thank you, Jay Campbell, technician St. George Auto, Brantford, Ontario, Canada

Dear Mr. Campbell, The Ford Passive Anti-Theft System (PATS) uses radio frequency identification technology to prevent theft. The PATS uses a specifically encoded ignition key that contains a transponder.

The system uses the powertrain control module (PCM) to enable or disable the engine. The instrument cluster communicates with the PCM over the SPC communication network in order to enable engine operation.

The PATS system is typically not compatible with most aftermarket remote start systems. The only system authorized by Ford that I am aware of is made by Chapman. I would check with the manufacturer of the system to be sure it is compatible with the PATS system.

Jeep MAP Codes

Dear Roy, The vehicle is a 1996 Jeep Cherokee Classic, VIN 1J4FT68S9TL290018, with a 4.0L engine and automatic transmission. This car sets a Code 108 (manifold absolute pressure [MAP] sensor voltage high) every time you start the car.

I replaced the electronic control module (ECM) twice, as well as the MAP sensor, with no results. I checked the connector at the sensor and have 5 volts there, as well as ground at the black wire.

With the connector plugged in, key-on, engine-off (KOEO), I have 4.6 volts at the signal return wire at the sensor and the ECM. With vacuum applied to the sensor, the voltage changes the same at both locations. I have also checked resistance of all three wires at both connectors. I even took the wires out of both connectors to inspect them.

I ran a new signal return wire to the map sensor to rule out electromagnetic interference (EMI), and I disconnected the throttle position sensor (TPS) and idle air control (IAC) and cleared codes, but it still reset. The only other sensor I see that shares that 5 volts is the crank sensor.

Please help before I have to set the thing ablaze and push it down a hill.

Daniel Jones, shop forman Dixie Auto, South Miami, FL

Dear Mr. Jones You will find three wires to the MAP sensor: A 5-volt supply, ground and signal. If you are experiencing a reoccurring P0107 or P0108, unplug the MAP sensor and check for 5 volts on one lead. Hook up a scan tool with KOEO and monitor MAP voltage. Use a jumper wire to jump the sensor ground lead to the signal circuit. The scan tool should read near zero volts. If not, test your ground circuit and check the signal circuit from the MAP sensor to the PCM for a broken wire.

Plug the MAP sensor back in and recheck the 5-volt supply. If the 5 volts drops all the way to zero when the MAP sensor is plugged in, then the sensor may be shorted internally and be causing the powertrain control module (PCM) to shut down the power supply. The 5 volts may not return until the key has been cycled off and on. The TPS can also short in a similar manner as the TPS and MAP shares a 5-volt supply. If either shorts internally, then they will both lose power.

The wiring from the MAP to the PCM runs along the firewall at the rear of the engine. Check the harness for rubbing on the fuel rail. It is not uncommon to find the wire from the map to the PCM is grounding to the fuel rail.