EFI relay question -- will relocating relay fix problem? Is upgrading wires needed?

[DaveFJ80]

Relocated EFI relay to dash - Is upgrading wires needed? (PICS

UPDATE -- Relocated the EFI relay and added pics below on post #6. Hopefully this will fix my problem, keeping the EFI relay from getting too hot and killing my truck while I'm driving on a hot summer day w/AC blowing.

_____________________________________________________________


I searched quite a bit, read quite a bit about this problem. I only have it happen to me when it's hot outside, the AC is on, and when I'm in stop & go traffic... never while I'm driving. Pulling the extremely hot EFI relay out and popping in a new cool one always solves my problem.

That said, I have a 2 part question......


1) When the truck dies in this case, is it because the EFI relay gets too hot? Or does it die because the wiring is corroded and causing issues (even though the relay feels burning hot to touch)?


2) If I relocate the relay to under my dash where it's cooler and away from the manifold, using 10 or 12 AWG wires on a pigtail.... will this solve my problem from my truck dying on me when it's hot, since the EFI relay will now be much cooler?

OR... do I really need to upgrade the engine bay wiring from EB1 and the ECU to the fuse box IN ADDITION to relocating the relay? Is the upgraded wires really necessary in the engine bay? Or will just relocating the EFI relay and keeping it cooler solve my problem?



Just trying to figure out whether I need to delve into a costly/timely project of rewiring everything, or just spending an hour and making a custom pigtail harness and running it inside the cab and mounting the EFI relay to under the dash.

 

[dallen341]

I had an 80 several years ago that had the EFI relay problem. I bought a commercially available relay (DPDT I think) and wired it under the dash by making a harness that plugged into the existing EFI relay socket. I use the flat spade connectors (male) to plug into the relay base.

Problem solved. Guy that owns the truck now has had zero problems.

 

[dallen341]

BTW, should have added that I checked the load across the relay and it was minimal. Don't recall the readings but something like 2 amps comes to mind. For whatever reason, I think engine bay heat was the greater contributor to failure than load across the relay. I believe I used 14 AWG wire.

 

[DaveFJ80]

dallen341 -
Thanks for the input. I remember reading your posts in other threads, and that's where I got the idea of just using spade connectors and running wires through the firewall and mounting the EFI relay underneath the dash.


However, going back to my original question.... did you end up changing or upgrading the engine compartment wiring that ran from the ECU to the fuse box?

And a side question.... after driving your truck around in this summer heat, can you feel the EFI relay and tell me whether it's hot, warm, or just normal feeling? Just wondering how much heat is transferred over the wires if I relocate the relay.

 

[dallen341]

I did not upgrade the wiring to the original EFI relay socket. Liek I mentioned, the load across the relay was only some 2 amps or so. The relocated relay (I used a standard automotive relay, not the Mr. T relay) did not get hot. In fact, before I finalized the wiring I had the relay sitting on teh passenger seat with a bunch of extra wiring to test it. Once I was satisfied all was good I finalized the wiring and no more problems.

 

[DaveFJ80]

Relocated EFI relay

Thanks for the input. I relocated my EFI relay tonight.... only took about a half hour and was pretty much a free mod since I had some 12 AWG wires, spade connectors, and flex conduit.

I left the wiring in the engine bay alone, so hopefully just relocating the EFI relay will keep it from burning up in heat from the exhaust manifold, as it's now located underneath my dash.

I drove around tonight for about 20 minutes and the relay never got warm, but then it was 11pm at night and it wasn't hot out. My real test will be driving the truck to work this Friday (55 mile round trip) with stop & go traffic and using the AC. I'm really hoping this fixes my problem of an overheating EFI relay that kills my car when it's hot outside.



Here are the spade connectors in the fuse box. I had 4 different color 12 AWG wires, so I just used them to keep things simple when plugging it in.





I drilled a small hole on the side of the fuse box cover, and it doesn't stand out at all with the flex conduit there.





Wires in the flex conduit going to the firewall.





The EFI relay. I had a few brand new ones so that's what I'm using.





Covered the wires up underneath the dash with the flex conduit and covered the contacts, but left the metal cover exposed to conduct heat. Tucked it up underneath the dash so that the relay has plenty of space around it. Also very easy access if I need to ever change the relay out.

 

[FrankTorres]

Good going Dave. Nice clean job.
This was my fix years ago and it has proven to be a trouble free permanent resolution to my EFI relay overheat.

 

[TrickyT]

It's hard for me to buy that your EFI relay is overheating just because it's located in the engine bay, no matter how hot LA is. So it'll be interesting to hear your followup in a month or two if this fixes the problem. Looks like you did a nice job with the wiring though. 12AWG was also a good choice. Now if the relay stills get hot it's because it's passing a lot of current through the contacts. The EFI relay has to power the fuel pump, oxygen sensor heaters, and ECU. Toyota doesn't publish the specs on what these relays are rated for, so we can only assume the engineers did their homework.

 

[DaveFJ80]

It's hard for me to buy that your EFI relay is overheating just because it's located in the engine bay, no matter how hot LA is.

It's not that hot in LA, but when it's over 90 during the middle of the day and I'm driving the truck hard with the AC on, there's a lot of heat generated underneath the hood. When my truck dies and I pull the EFI relay out, it's always very hot. But then so is is the horn relay and metallic parts, so it's telling me the exhaust manifold is the main cause of the heat.

I'll continue to keep an eye on the relay to see if it gets hot while driving, as that will tell me if it's the current. But if the relay stays cool(er), then I believe this should solve my problem.

Toyota doesn't publish the specs on what these relays are rated for, so we can only assume the engineers did their homework.

Yup, Toyota engineers did do their homework.... on the 93+ FJ80's, when they relocated the exhaust manifold to the other side on the 1FZ .

 

[Motleyone]

I have had the same problem with my 92 here in the AZ heat. I had the AC on and was pulling a small pop up camper. The heat in the fuse box is amazing. The relay cant be touched and pliers are needed to remove it. I put a new relay in and was good for the rest of the trip. The relay was still very hot the entire time. I will keep an eye on your thread and will do the relocation if it stays cool for you.

 

[jonheld]

FWIW, the EFI circuit draws about 6.25 amps@2500 RPM.
The main issue is the crimped wire connections in the fusebox. With time and heat these will go intermittent/or become resistive.

I replaced all EFI wiring in the fusebox and used a plastic case EFI relay from a Camry (direct drop in) and it has been fine for the last 8 or 9 years.

http://www.sdsysdesign.com/tlc/relay.html

 

[DaveFJ80]

FWIW, the EFI circuit draws about 6.25 amps@2500 RPM.
The main issue is the crimped wire connections in the fusebox. With time and heat these will go intermittent/or become resistive.

I replaced all EFI wiring in the fusebox and used a plastic case EFI relay from a Camry (direct drop in) and it has been fine for the last 8 or 9 years.

EFI Relay Pics 4 U

Thanks for the info. That will most likely be my next step depending on how this turns out.

BTW, I checked out that link before and it appears that the info and pics have been removed.

 

[itbrokeagain]

I was having some issues on my 80 and the first thing I went to was the efi relay. The relay had been moved because the fuse box was melted where the relay had originally sat.

 

[jonheld]

BTW, I checked out that link before and it appears that the info and pics have been removed.

Uhh, no. All info is still there. I haven't changed or updated the site in 2 years.

 

[4Crash]

New to this forum and really appreciate all I have learn trolling the last few weeks.

I have had my '92 LC for 7 years. About 1 year ago it started blowing the EFI 15amp fuse during the summer. I just finished relocating the relay inside the cab (Thanks DaveFJ80) and let it idle for a long time instead of driving it. I thought that would narrow down the problem-short from something rubbing or heat related. After 2.5 hours at idle the EFI fuse blew again.

Looking for thoughts on what to try next.