No Power to ECU

[BoostGetsULaid]

So my car was stolen afew months back and I am putting it back together. Got everything back. The car ran before it was stolen. It's a S13 with a red top sr20.

I checked the Fuses (next to battery). 10A "Eng Cont" & FL25A ENG CONT. I Decided to test the FL25A prongs. So I removed that fuse and tested both sides, they both have power with out the fuse in (?)

The car turns over but no spark or fuel. So I checked the ECU wiring.
38 & 47 - ECU Power (Blk/White) - No Power
39 & 48 - ECU Ground (BLK) - Ground Good
46 - ECU Back Up Power (Red) - Good Power
104 - Fuel Pump Relay (Blk/Pink) - Good Power
36 - Ignition Switch (BLK/Red) - Good Power When Ignition is On
4 - ECU Relay (Red/Blk) - Good Power (???)

So From my understanding, isn't the 36 wiring suppose to send power to the ECCS/EGI relay to tell it to ground wire 4 when switched to ON which grounds the ECU allowing the ECU to turn on?

When I turn the ignition on, I do not hear my fuel pump. But I used my 104 wire (Fuel pump relay) and jumped both my ECU power wires with the 104 wire and my fuel pump turned on. So I am really confused. on why my ECU Power wires aren't getting power.

The wiring harness has been repaired using soldering and shrink wrap a month before it was stolen and the thieves didn't touch anything wiring wise really other than my radio and attempt to pull my alarm out, but they failed and only managed to damage my antenna. Only thing I could think of that he could of done was tired to start the car and do something to cause like the ECCS/EGI relay to get fried.

Thanks

[maverickmotorsports]

Try swapping the relays around and see if the ecu will power up. Can you hear them click on when you turn the key to the on position?

Pin #4(red/black) is a switched ground. There will be no power going through that wire.

I would also check ALL of the fuses. Who knows what could have popped while the thieves were ripping shit apart.

[hassanbakar123]

+1 on check fuses
is everything grounded.

[BoostGetsULaid]

I think i may have switched the relays around afew months back. I don't remember. But I'll try again tonight. I've checked all the fuses even ones that don't have to do with the vehicle starting and operating.

Yeah, from my understand. The #4 is a switched ground. I was wondering why it was getting consistant power while in ON. This may be the problem why the ecu isn't getting power.

I was talking to the Nissan master tech at my work and he says, It may be the ECU itself. But work is slow and I don't want to go out and buy a new ecu and have it not be my issue.

Thanks again

[cotbu]

104 is a ground trigger, do not send power down that wire.
If you know your ecu is good remove it. test all wire and whatnot while the battery is disconnected. The problem is in the harness.
trace wire for pins 38 & 39, you could even power those temporarily to make sure the ecu is functioning correctly. If it's not, (functioning) then you have a lot more work to do.

P.S. you can trigger the fuel pump by jumping the relay socket, sending 12v straight to the fuel pump. this bypasses the ecu trigger.

The ecu being fried will not make it's power source not function with out blowing a fuse first.
have u checked the main 75-100amp fuse just curious.

[maverickmotorsports]

http://zilvia.net/f/tech-talk/303116-s13-sr20det-painless-ezwiring-schematic.html

i wrote that a while back for painless/custom wiring. it's not accurate for OEM stuff but the general outputs/inputs for the ECU are all listed.

[BoostGetsULaid]

so i went a head and retested all the fuses. Last time i used a multimeter and tested resistance and visually checked the fuses. this time i used a test light and tested the top test points of the fuses. All fuses are good.

The car has been sitting so I have it on the charger. ran a wire from the battery w/ a 10 fuse on it and put it into both simulated power. I try to turn it over and I hear no Fuel pump turn on now. I try to turn it over and it attempts to turn over and has only half a crank before dying. So I'm currently continuely charging it. But I find it strange that the fuel pump doesn't turn on while everything else turns on when it did before.

Frustrated I RE-Tested all the wires on the ecu side. So I took the cover off and test the ecu from inside on the circuit board after it the plug. I still have the 38/47 wire getting power. and the car in "ON". Found that on the #36 Ignition Switch Wire. I am suppose to be getting Ground at this. But on the Harness/Plug side I am getting power. I tested this but on the ECU's Circuit board, it comes up as a ground. Whenever I tap it to check it with my test light on the ECU side I hear a clicking from the engine. I believe it may be the Relay clicking. But without a second person, I am not sure where exactly it is coming from :'(

Anything left blank is either missing or am not getting anything from

101 W/B Fuel Injector # 1 Drive Input POWER
102 O/L EAI AIV Control Solenoid Output
103 G/B Fuel Injector # 3 Drive Input POWER
104 B/P Fuel Pump Relay POWER
105 R/W Fuel Pressure Control Module GROUNDED
106 G/Y A/C Relay
107 B Fuel Injector Ground GROUNDED
108 B Fuel Injector Ground GROUNDED
109 R ECU Current Return POWER
110 Y/B Fuel Injector # 2 Drive Input POWER
111 O/B Turbo Boost Pressure Control Solenoid
112 L/B Fuel Injector # 4 Drive Input NOT GETTING POWER
113 SB Auxiliary Air Control, Idle Speed Control GROUNDED
114 Br/Y (unknown function)
115
116 B Fuel Injector Ground GROUNDED
1 R/W Ignition Signal # 1 GROUNDED
2 R/Y Ignition Signal # 2 GROUNDED
3 Y/R Tachometer Signal Output GROUNDED
4 R/B ECU Relay Getting Constant Power @ "ON", Suppose to be Ground
5
6 B Ignition Signal Ground GROUNDED
7 G/B Receive (Control Unit Data Reception) RX POWER
8 R/G Ignition Signal # 3 GROUNDED
9 R/L Ignition Signal # 4 GROUNDED
10 G/Y A/C Relay
11
12 P/B Automatic Transmission Gear Select
13 B Ignition Signal Ground GROUNDED
14 G/W Clock (Synchronization Signal) CLK GROUNDED
15 G Transmit (Data Sent From Control Unit) TX
16 W Mass Air Flow Sensor Signal Input GROUNDED
17 B Mass Air Flow Sensor Ground GROUNDED
18 L/O Engine Coolant Temperature Sensor Input GROUNDED
19 W Oxygen Sensor Input GROUNDED
20 W Throttle Position Sensor GROUNDED
21 B Sensor Ground GROUNDED
22 W Cam Angle Sensor 180 Degree Signal GROUNDED
23 G/R CLK Data Link Connector For Nissan Consult GROUNDED
24 / Malfunction Indicator Lamp (Add Wire For Check Engine Light)
25 O/B Exhaust Over Temp Warning Lamp Output
26 L/Y Exhaust Temperature Sensor
27 W Detonation/ Knock Sensor Input
28 W/L Automatic Transmission TPS (Kick Down Switch)
29 B Sensor Ground
30 W Cam Angle Sensor 180 Degree Signal
31 B Cam Angle Sensor 1 Degree Signal GROUNDED
32 Y/G Vehicle Speed Sensor POWER
33
34 O Start Signal GROUNDED
35 G/O Park/ Neutral Position Switch GROUNDED
36 B/R Ignition Switch GROUNDED On ECU Side, Power on Harness side (???)
37 Lg/R Throttle Position Sensor Power Output GROUNDED
38 B/W ECU Power Simulated POWER
39 B ECU Ground GROUNDED
40 B Cam Angle Sensor 1 Degree Signal GROUNDED
41 L/G A/C ON Switch POWER
42 Br/Y Automatic Transmission Gear Select
43 Pu/W Power Steering Oil Pressure Switch (Helps Idle When Turning Wheels) POWER
44 Lg/R Automatic Transmission Gear Select
45 L/W Intake Air Temperature Sensor
46 R ECU Backup Power POWER
47 B/W ECU Power Simulated POWER
48 B ECU Ground GROUNDED

[240sx-pat]

Man this is THE EXACT SAME SHIETZ that I did (except for testing inside the ecu circuit, I tested at the ecu connectors)

38 & 47 - ECU Power (Blk/White) - No Power
39 & 48 - ECU Ground (BLK) - Ground Good
46 - ECU Back Up Power (Red) - Good Power
104 - Fuel Pump Relay (Blk/Pink) - Good Power
36 - Ignition Switch (BLK/Red) - Good Power When Ignition is On
4 - ECU Relay (Red/Blk) - Good Power (???)

I got the same result.


I'm pretty much in this situation that you were in before ( assuming you've already fixed it). How did you fix it? please tell me it was because of your ECU

[pbnjake]

I am in this exact same boat right now except I was driving down the highway and the car shut off completely and I'm not getting power to the ecu. How is it you guys went about fixing this?

This post is old but I'm throwing a hail Mary

[snipper17]

Anybody have any luck finding out why ECU Pin #4 had power and wasn't grounding? Just put a power FC in and having the same issue