2000 S40 - Cranks, no start- 21.2 mVolts at Engine and Fuel fuses

bobcameron · Post by **bobcameron** » 17 Oct 2016, 11:38

I have a cranks over fine, but no start condition. I checked the voltage at the fuse box for both the fuel (pump) and the engine. Both fuses are allowing 21.2 mVolts through. I checked each injector positive wire, same voltage, 21.2 mVolts. i confirmed continuity with ground, from injector ground wires to the firewall, as well as from engine block to the firewall. All the rest of the fuses in the fuse box under the hood are at 12.2 volts. I have no codes, and if I remove any connector from any sensor, it will throw a code for that sensor. This leads me to believe that the ECU is still functioning. I picked up a used ECU (no keys or ring), but get the immobilizer warning when trying to start. I do not know if it is possible to reprogram this myself, and can not find a repair shop in Charlotte, NC that will work on it besides the Stealership. Any suggestions on what to check next?
2000 S40, 1.9T, auto. 156000

Post by **alschnertz** » 18 Oct 2016, 15:02

I think you are mistaken reading 21.2 volts.
I don't know how you can be registering more voltage than the battery.
Are you sure your tester is set to DC voltage?

bobcameron · Post by **bobcameron** » 19 Oct 2016, 12:36

I am positive, I measured at the battery posts and get 12.2 volts. Measured at the fuse block, all other fuses get 12.1 volts. When measuring at the "Fuel" and the "Engine" fuses, I get 21.2 volts. I get the same reading if I ground the meter on the block, on the firewall, on any body ground connected wire, or on the battery ground.

Post by **alschnertz** » 19 Oct 2016, 15:17

Are you getting the 21.2 volts during cranking or just when it's sitting?
This symptom is very unusual.

bobcameron · Post by **bobcameron** » 20 Oct 2016, 06:09

I have measured this while not running, not during cranking. There is 21.2 volts at the fuse for engine and fuel, at the positive cable going into each injector, and at the positive cable going into the fuel pump. There is fuel pressure at the injector rail, measured at 47 psi, ignition on, not cranking. I recently installed a new fuel pressure regulator to fix the low pressure there. the injectors seem to be the only thing not firing, so I am going to pull apart the wiring harness and trace continuity for each cable.

Post by **alschnertz** » 20 Oct 2016, 14:57

I'm at a loss and hope someone will chime in.
I just can't figure out how one 12 volt battery can supply 21 volts.
Good luck.

bobcameron · Post by **bobcameron** » 21 Oct 2016, 12:15

Retested and found that the higher readings were mili Volts, not volts. (Adjusted Heading to reflect for anyone else searching)
So, I am seeing mili volts at the fuses for Fuel and Engine. I removed and reseated the ECU, retested, same thing. I used a replacement ECU, reset the system with 5x door lock unlocks. Same symptom, cranks no start, no fuel out of injectors, they are not firing. I have fuel pressure at the rail of 47, 12.1 volts at the positive cable into each injector, and spark. A test light shows no ground from injectors negative cable during what should be firing. There is ground continuity from the engine block to the ground points in fender, frame, firewall bolts,etc, near zero.
I checked the fuses again, same readings. I am going to start taking the wiring harness apart to test for continuity, looking for a short, unless somebody has a solution for this extremely low voltage at these two under hood fuses (Fuel and Engine). all other fuses are at 12.1 volts. ECU is not showing any codes unless I disconnect a sensor. I was contemplating an issue with the immobilizer, but the warning light is working just as described in the service manual, 3 seconds or less illuminated when cranking, then it goes off.

Post by **alschnertz** » 23 Oct 2016, 05:07

That makes more sense.

What resting voltage do you have at the battery?
I'm not sure how sensitive the S40 is but I've heard of other cars that won't start without 13.5 V or so at the battery (Mazda MPV comes to mind).
Maybe you could try jumping it or at least using a different battery before you pull the harness apart.