Fuel pump circuit fuse m22

Neither. I cannot find that circuit on the diagram. Where are you measuring and what is the wire's color?

The fuel pump relay turns on for one second when you turn on the ignition switch, then it turns off again. It gets turned back on during engine rotation, (cranking or running). That is the safety feature on all fuel injected vehicles. In the event of a crash that ruptures a fuel line, the pump would dump raw gas onto the ground, creating a serious fire hazard. Instead, with no fuel pressure, the engine will stall. Once stalled, no more signal pulses will show up from the crankshaft position sensor or the camshaft position sensor. That tells the Engine Computer to turn the automatic shutdown, (ASD), and fuel pump relays off. That stops the fuel pump.

Even if the fuel pump relay was bypassed or stuck on, fuel pumps are designed to run continuously, and it would kill the battery long before the pump's motor burned out. I am sorry that I am unable to post the diagram. If you are back by the pump, the wire that feeds the pump is dark blue/orange. For accuracy, voltage readings should be taken with the connector plugged in. There will be rubber seals around the wires where you can back-probe them.

It looks as though the bus bar that feeds those fuses should only have power with key on.

See the wiring diagrams below for more information.

Hey CRAIG5820,

The fuel pump relay is integrated into the TIPM which you may be able to fix by trying the find the relay which is soldered in. Turn the key on and feel for the relay that clicks. Here is a diagram to help with the location.

Please let us know happens so it will help others.

Best, Ken

What happens when you try to crank the engine? Have you checked the battery voltage? Buzzing relays is a common symptom of a battery with one shorted cell.

Have you checked for spark?

Rats. With the tests you've done, it does appear the computer is not grounding the fuel pump relay. It needs pulses from the crankshaft position sensor and the camshaft position sensor to do that. If one of those signals is missing, there won't be spark.

Listen for the hum of the pump for one second after turning on the ignition switch. If you hear that, the fuel pump relay is good and the computer has control of it. If you don't hear it, suspect the computer, but before you condemn it, ground the relay coil right at the computer plugs. If the relay clicks on, that will confirm that wire between the relay and computer is okay. Next, there should be four ground wires, two listed as "signal" grounds and two as "power" grounds. The best test for them is a voltage measurement while the relay is bypassed and the engine is running. If you find more than a couple of tenths of a volt, check that wire for a corroded connection to the body.

Sad to hear it was the 'puter but happy it's solved. Chrysler had extremely little computer trouble back then. I'm still on my original one in my '88 Grand Caravan daily driver with 230,000 miles.

Hope your back is better.

I know all about "book smart" too. I taught auto shop for nine years with another instructor who taught straight from the text book. That doesn't help someone be successful on the job.