Faulty main relay - 2008 Acura Tl

Code 78 APPS Main and Code 79 TPS Main are diagnostic trouble codes (DTCs) that can appear on a 1997 Mitsubishi Pajero. Code 78 APPS Main: This code indicates that the APPS (Air Pump System) Main relay is not working properly. The APPS relay is responsible for supplying power to the air pump, which is used to control the air-fuel mixture. Code 79 TPS Main: This code indicates that the TPS (Throttle Position Sensor) Main circuit is not working properly. The TPS sensor is responsible for sending information to the engine control unit (ECU) about the position of the throttle valve. If either of these codes appears, it is important to have the vehicle diagnosed by a qualified mechanic to determine the cause of the problem. The mechanic may need to test the APPS relay, the TPS sensor, or other components in the fuel system. Here are some possible causes of Code 78 APPS Main and Code 79 TPS Main: Faulty APPS relay: The APPS relay may be faulty and not be supplying power to the air pump properly. Faulty TPS sensor: The TPS sensor may be faulty and not be sending accurate information to the ECU about the position of the throttle valve. Clogged air filter: A clogged air filter can restrict airflow to the engine and cause the APPS relay to overheat and malfunction. Low fuel pressure: Low fuel pressure can cause the APPS relay to overheat and malfunction. Faulty wiring: The wiring to the APPS relay or TPS sensor may be damaged or corroded, causing the codes to appear. If you are experiencing problems with your 1997 Mitsubishi Pajero and either Code 78 APPS Main or Code 79 TPS Main appears, it is important to have the vehicle diagnosed by a qualified mechanic to determine the cause of the problem and to get it repaired as soon as possible.

Hello
When you are having this faulty code P1640 Main Relay Control Circuit.

To solve this open your Engine Bay Fuse box,
look for the relay named CRI and fuse CRI ECU remove any of this fuse or relay.
Then start your car for 5 mins.
Switch off and dragonize it again.

fault code is solved.

take it out and have it tested
fuel pumps fail mainly from running without fuel in the system
other problems indication a pump problem come from
faulty pump relay , faulty fuel pressure regulator--controls the fuel pressure and the pump relay ,--- wiring, bad ground for the pump, EVAP --not allowing the tank to vent and the pump runs in a vacuum situation or problem ECM not passing the requirement to pump onto the pump relay to start pumping

The Bentley Manual shows the fuel pump relay in the box on the passenger side of the car under the hood. Looking toward the drivers side the pump relay is the second on from the passenger side. It is fuse #23. Looking at the bottom of the relay the pins clock wise from 12 o'clock are 30-87-85-86. The third one from the passenger side is the main relay. It is usually white. "The main relay is energized via the DME engine control module and supplies power to many of the DME components and subsystems, including the fuel pump relay. If this relay is faulty, the engine will not start."

Faulty relay or where relay plugs in check underside wiring give the relay box a good spray with penatrating oil(relays removed)

MAKE VECHICLE NOT OVER HEATING CHECK COOLING LEVEL.IF ALL IS GOOD CHECK FOR SPARK AND FUEL.DO CODE SCAN FIRST,COULD HAVE FAULTY ASD RELAY,FAULTY FUEL PUMP OR RELAY,BAD ENGINE COOLANT TEMPERATURE SENSOR, FAULTY EGR VALVE, CODE SCAN MANY THINGS WILL CAUSE ENGINE SHUT OFF.

left side near the ECU under the dashboard

Could be... Broken Timing Belt - Faulty Ignition Coil - Faulty Main Relay - Faulty Distributor - Faulty Fuel Pump

the main relay is located under dash(behind knee bolster) just left of steering column. it should be gray in color with one screw on the bracket. this relay is replaced often for quitting and no-start conditions. other problem for the same symptom is faulty distributor

You have been initiated into the faulty main relay club. Check some of the other posts about this problem; it can be complicated. Also look under 1997 Honda Civic. The main relay is also a problem for them.