Reset ECU and now it wont start!

[knussear]

Hi all new to the forum and new to me 1995 4Runner owner. Got a nice truck V6 3.0, Manual Trans. Was running yesterday and had 2 codes when I picked it up 25 and 71. Looking under the hood it had broken wires on the ECU/exhaust Temperature sensor so I replaced the sensor. I Pulled the 20 amp ECU fuse to reset it, and now the vehicle WILL NOT START. Turns over all day, but no fire. Checked all fuses - good, There is power at the fuse box to the ECU, not sure how to check power AT the ecu. Only other thing I did was change the air filter - wondering if I tweaked something on the MAF?. Re-attaching the code jumper yields no check engine light at all, no solid, no blinks, NADA. Any ideas on what else to try? Had the truck 1 day and I broke it. This one is baffling me.

 

[RonJR]

It sounds like the ECU is not getting any power. It may be that a tab or blade in the 25 year-old fuse box, or a wire underneath it, broke when you pulled the EFI fuse. Check downstream of that fuse. Pull the EFI main relay and check to see that pins 1 and 5 have 12V during cranking.

Here is a wiring diagram for the engine related stuff.

 

[knussear]

Thanks for the reply. I ended up replacing the relay, and then finding that the connectors in the 25 year old fuse box were not connecting tightly enough. I was able to reach in with a small awl and get them to close enough. Off to the next adventure!

 

[knussear]

It sounds like the ECU is not getting any power. It may be that a tab or blade in the 25 year-old fuse box, or a wire underneath it, broke when you pulled the EFI fuse. Check downstream of that fuse. Pull the EFI main relay and check to see that pins 1 and 5 have 12V during cranking.

Here is a wiring diagram for the engine related stuff.

Following up. I've had intermittent failure on the new relay. Tracked all wires down and I'm now finding that the fuse box in the lower left driver kick panel is the culprit. I get failure once the car has warmed up, and if I move the fuse box pushing forward or rear I can get the car to quit or start. So I would like to get that out of there or at least move it where I can inspect it more closely. I got everything in the way out of there (e.g. cruise control box, door locks box, etc.), and removed the bottom bolt, but I cannot figure out what mechanism will let me loosen the top of the box. Does anyone have any tips about how to get at this?

 

[dansoore]

Pull the EFI main relay and check to see that pins 1 and 5 have 12V during cranking.

 

[knussear]

Pull the EFI main relay and check to see that pins 1 and 5 have 12V during cranking.

Replaced the grey box behind the fuse box called "relay integration" and all is working well now.

Looks like this one.

 

[Middlefingergod]

Glad you got it figured out. I'm having issues with mine and cant get it figured out.