I have a 2005 Toyota 4Runner 4.7 v8 4wd. I recently hydro locked the engine and shot a connecting rod through the block, long story short I got another engine with 132,000 miles on it and swapped them. Turn the key and nothing happens, electrics work, starter does work as I sent direct power to it separately and it turns over it just doesn’t send power when it’s plugged into it’s normal connector. I checked fuses, connections and they all seem fine. It’s the original wiring harness and ECM, which both worked on the last engine after the hydrolock. Any suggestions? I also checked the neutral safety switch, and rocked the shifter back and forth.
Well since you asked for suggestions.........
You should continue with your "What If?" approach.
You've determined (by "jumping your starter) "what if" the starter gets power?
Answer: The starter works.
So now move back in the circuit to the next logical place. The starter relay. (engine compartment fuse box)
What if the starter relay is bad?
Check the STA fuse and the AM1 fuse and then swap the Starter relay with a known good relay.
Still nothing?
Pull the relay out and test the relay's sockets in the fuse box.
What if the wiring between the starter relay socket and the starter is damaged/shorted/open?
(Orange circuit)
Use a jumper wire to provide battery voltage (12 volts +-) to the Starter relay pin socket that goes to the starter solenoid..
Starter doesn't spin? There's a problem with the wiring/connectors between the starter relay socket and the starter. Investigate and determine the problem.
Starter spins? Wiring between the starter relay socket and the starter is good. Move on to the next "What if?"
What if there isn't battery voltage (12 volts+-) being provided to the relay socket for the starter to work?
(Red Circuit)
Use a multimeter or test light to determine if the relay socket pin that provides battery voltage to the starter solenoid (when the relay's coil is energized and the relay's switch is closed) has battery voltage (12 volts+-) when the key is in the Start position and the vehicle is in Park/Neutral.
No power at the socket? Investigate that side of the circuit for the problem.
There is battery voltage at the socket? Then wiring to that relay socket pin is good. Move on to the next "What if?"
What if the relay's coil socket isn't grounded and it can't be energized by the positive voltage "signal" from the ECM (computer)
(Green Circuit)
Use a multimeter or test light to determine that there is ground at the relay's coil ground socket.
No ground at the socket? Investigate the wiring/connections between that relay socket and the Ground point.
Ground is present? Move on to the next "What if?"
What if the ECM (computer) isn't sending the positive voltage "signal" to the relay's coil socket to energize the relay's coil and close the relay's internal switch to complete the starter circuit when the Key is in the Start Position?
(Blue Circuit)
Use a multimeter to test for voltage at that relay socket pin when the key is in the Start position. There should be between 10 and 12.5 volts to energize the Starter Relay's Coil.
If there is between 10 and 12.5 volts here when the key is in the Start position then the ECM (computer) is sending the positive voltage "signal" to energize the relay's coil.
If there isn't 10 to 12.5 volts at the socket (Key START) then move to the Passenger Compartment Fuse Box and test fuse numbers 34 and 39 (5 Amp) (in the Key Start Position)
If those fuses are good then move to the next "What if?"
So, What if the ECM (computer) isn't sending the positive voltage "signal" to energize the Starter relay's coil?
You'll want to test the pin/connector on the ECM to confirm it's actually sending the positive voltage "signal" to the Starter Relay.
If it is, then there's a problem in the wiring/connectors from the ECM to the Starter Relay socket.
If it isn't then you'll have to examine the circuit to determine why that's happening to rule out a bad ECM. The Neutral Safety Switch has to be functioning as well as the VSS sensor (among other inputs) or the ECM won't send the positive voltage signal to the Starter Relay (when the ECM is functioning properly)
You'll want to carefully examine and understand the starting circuit and parameters the ECM uses to send the positive voltage "signal" to the Starter Relay. Buy a 1 year subscription ($30) to ALL DATA DIY which will provide that technical information for your 2005 Toyota 4Runner 4.7
So here's the Starter relay socket wiring diagram. I color coded each circuit with the individual "What if" test.
Here's the referenced fuses in the
Passenger Compartment Fuse Box
Which relay pins go where?
Compare the map on the Starter relay to the wiring diagram and using your multimeter you can determine which pin sockets do what.
also check the AM2 fuse
Thank you so much, I’ll check all of this tomorrow and let you know.
I’ve determined the blue line (ECM) is only sending 4 volts instead of the required 10-12. All of the fuses look good so I’m gonna need to test the ECM. Also the OBD reader doesn’t come up with any codes concerning the ecm
Well if your Hydra like the engine odds are you suck water into everything if you went through deep water you could ruin the electronic start with my video fixing a car that cranks but doesn't start up Scotty
Where is that video? Do you know where the start is?
Sorry, it’s not cranking either. It’s not a fuel or air problem it’s an electrical problem after an engine swap.