Car won't start after pulling ECM fuse

WagonMountainMan · Post by **WagonMountainMan** » 13 Jun 2020, 23:30

Hello and thank you in advance for reading.

My brand new (to me) Volvo will not start after pulling the ECM fuse. It tries to crank but will not start. I was reading on forums I could possibly reset the temperature gauge problem I was having by pulling the ECM fuse. Now what was a running vehicle, is not running. If anyone has any insight how to reset the computer please let me know. I am receiving no error messages on dash, I have a '03 2.5L xc70 Please please help!!! Thank you.

Post by **RickHaleParker** » 14 Jun 2020, 02:21

What is the number of the fuse you pulled and where is it located? There is more then one fuse box.

EngineeringBloke · Post by **EngineeringBloke** » 14 Jun 2020, 10:36

Was engine running when you pulled the fuse? If not, what was the position of the ignition key?
Have you replaced the fuse?

WagonMountainMan · Post by **WagonMountainMan** » 14 Jun 2020, 19:49

I pulled Fuse # 6 "ECM/MAf/Injectors, on the driver's side under the hood, car was off. The fuse is still good. Thank you so much in advance.

WagonMountainMan · Post by **WagonMountainMan** » 14 Jun 2020, 19:49

Also, key was not in ignition at all.

Post by **RickHaleParker** » 14 Jun 2020, 20:44

Check the condition of the fuse socket. Clean it with MAF cleaner or electrical contact cleaner.

WagonMountainMan · Post by **WagonMountainMan** » 14 Jun 2020, 20:52

I feel like a dog with its tail between its legs after pulling fuse six, and letting it sit for 30 minutes or so, I put the fuse in slot five not six. Placed it back in six, car fired right up. If this thread can be of any help; this ordeal started with a temperature gauge not registering at all. And a blown radiator. Put the radiator in, realized I had no gauge for the temp. Bought a new temperature sensor. Nothing changed on dash. Pulled the ECM # six fuse and the gauge is Finally READING. Now, I have no fan unless the AC is on. It went to operating temperature so maybe the computer is resetting? I'm debating putting a thermostat in, as the upper hose seems stiff. That's my update. I'm quite sure than won't make the fan work nor do I understand if the car can get to operating temperature with a faulty and closed thermostat. Any insight if extremely appreciated. The lesson for me today is, two heads are better than one and when that's not a option take a breath and reevaluate your current situation. Thanks for any knowledge or advice!

Post by **RickHaleParker** » 14 Jun 2020, 21:41

Checking the fuse socket was the solution.

Post by **jonesg** » 14 Jun 2020, 22:27

WagonMountainMan wrote: ↑14 Jun 2020, 20:52 I feel like a dog with its tail between its legs after pulling fuse six, and letting it sit for 30 minutes or so, I put the fuse in slot five not six. Placed it back in six, car fired right up. If this thread can be of any help; this ordeal started with a temperature gauge not registering at all. And a blown radiator. Put the radiator in, realized I had no gauge for the temp. Bought a new temperature sensor. Nothing changed on dash. Pulled the ECM # six fuse and the gauge is Finally READING. Now, I have no fan unless the AC is on. It went to operating temperature so maybe the computer is resetting? I'm debating putting a thermostat in, as the upper hose seems stiff. That's my update. I'm quite sure than won't make the fan work nor do I understand if the car can get to operating temperature with a faulty and closed thermostat. Any insight if extremely appreciated. The lesson for me today is, two heads are better than one and when that's not a option take a breath and reevaluate your current situation. Thanks for any knowledge or advice!

for future reference, a computer safe test probe allows the fuses to be checked without pulling them.
I don't know about the cooling fan but if the guage isn't going into the hot zone, the fan probably doesn't need to activate.
It cycles automatically with the AC, so at least you know the fan works.

Post by **RickHaleParker** » 14 Jun 2020, 22:41

There are better probes out there that will automatically tell you if you are probing a voltage source or a ground.

I got one of the Harbor Freight probes and the fulcrum rivet on the clip broke out after only a couple of uses. Also the LEDs on the Harbor Freight probe are not very bright, hard to see in sunlight. Look for something better constructed.

There is a Actron CP7852 on Amazon for $9.99, free shipping. These usually go for ~ $30.00.
Actron is a tool division of Bosch Automotive Service Solutions.

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