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Hi all New 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, not sure how to check 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. Any ideas on what else to try? This one is baffling me.
Last edited by knussear; Feb 18, 2020 at 07:37 PM.
Which is definitely not enough to run the ECM. I'd check the voltage on each side of the MFI/EFI fuse (there are metal tabs on the fuse for that purpose). Then work in the direction of poor voltage.
Moving forward to the EFI Main relay. First check the IGN fuse (same way) as that powers the coil of the relay. Using your stethoscope (the tube from a roll of paper towels will work), listen for the relay to click with key-on. Even if it clicks, the contacts may be bad, so pull it and test the relay. (1-2 is the coil, 3-5 NO contacts) Even if the relay is good, you still have some W-R wire (and at least two connectors) on the way to B+. But you get the idea.
OK Found the COR - and checked it out per the shop manual page that someone had posted. All working fine. Also have only 0.5 V at the B+ there when turning key. Also checked AFI relay - functioning fine, but NOT activating when key is turned. 12.5 V on both sides of the EFI fuse in the engine bay.
Checked all fuses inside the vehicle - have 12 on both sides on all, including lights and "defog" when the rear defrost and lights are switched on. All fuses in the engine bay read the same, and I have power across AM1 and AM2 as well as the big 80A one. Where could I be losing power? is there a fusable link anywhere?
Boom. Solved it. I checked the EFI relay, and seemed to test well on the bench. However - in the car another story. I removed it to check 12V at the control circuit side. Key on 12V - perfect, then at the Power circuit side - key on 12 V perfect. So I rigged up a quick jumper wire to see if the rest of the beast would work. Started first try.... and my 25 and 71 codes are gone. Off to get a new relay. Thanks for all the help here. I understand the truck much better now, and you really helped me get there!
Let us know how that turns out. If the relay tests "good" on the bench, replacing the relay shouldn't solve anything. I would suspect something wrong in the socket or associated wiring, which your jumper bypassed.
Yes - turns out you are right. I'm getting intermittent issues even with the new relay. I need to run down whats breaking the ignition on power irregularity at the + side of the EFI relay control circuit. Traveling this weekend, but will be running that bug down next week.
OK - used some jumper wires to test things out, and all are functioning. Turns out the contacts in the relay connections on the engine side got a bit loose. I used an awl to close them up a bit and I'm back in business. Now I'm getting codes 14 and 25, and tracking those down.
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?
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?
Should be a clip, see the first post of This thread
OK Opened up a new box of curse words, drew a little blood, and got it to swing forward enough to get at the piece that was cutting things off when I manipulated it. Pretty sure this is the horcrux that contains my issue. Serviceable or just replace?
Feb 17, 2020 | 05:01 PM
