Market / Need for a solid state Fuel control / edic relay

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Raggsokk

Raggsokk

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Recently I was so lucky to get hold on a beautiful 1990 HJ60, my dream car for a long, long time.

As with many I have trouble with my Fuel control / EDIC relay.
There are used relay to be bought, some reproduction replacement to be bought, but I am not quite happy with either solution. Used is risky and the replacement requires a harness swap and is still a mechanical relay.
Being an electronics engineer, I wish to replace the relay with a solid state version to hopefully increase the reliability and as a project to entertain myself.
The reason behind this post is to try to figure out if there is a wish / need for a solid state replacement for others out there?
I do not plan on making much if any profit, and I will probably make it open source, but it is an significant increase of work to make sure others can use the design instead of a one off for myself.
I am quite fond of projects and would like to do it, but if it is only for my car I will probably just remove the relays and add some simple transistor logic on the original pcb.

Playing around with the idea one could think the following possibilities:
1)
Original look:
Open up the relay and remove the old pcb, move over the old wire harness with the connector.
This requires soldering and a bit of work, but one could toy with the idea of supplying a replacement relay with a deposit until your old one is returned, then it would be plug and play for the end user.
2)
New replacement relay:
New relay molded in conformal molding to avoid any moisture ingress, new connector on harness, requires a change of the harness connector in the car.
The original connector could be badly corroded, then the above solution would take care of both problems.
3)
As above but with a reproduction connector for a plug and play solution.

It would be easy to make a 12v and 24v compatible version requiring no change for either voltage, but I do not know of how many other relays there are need for? It might be possible to make one design that is easy to configure for several version, i.e cheaper.
I have the 28590-56100 with three relays inside. I know I have seen photos of others with two relays inside etc. If I am to do this I will need some help for sure to figure out what the need is.
 
bcsteel

bcsteel

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I have 2 24v trucks. 1984 bj42 24v and 1989 hj61 24v that I can help with as much as possible. Would like to be part of this and have a better solution than used parts that are 30 plus years old.

My personal preference would be new relay and sealed. Reliable etc…
 
Raggsokk

Raggsokk

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I have 2 24v trucks. 1984 bj42 24v and 1989 hj61 24v that I can help with as much as possible. Would like to be part of this and have a better solution than used parts that are 30 plus years old.

My personal preference would be new relay and sealed. Reliable etc…
Do you know what part numbers your relays have?
I agree with you regarding a fresh molded one should be best. Would you be comfortable with replacing the connector in the wire harness with a sealed type or do you prefer to keep the open stock connector?

I also realized that people might get a bit skeptical to the idea, my first post on this forum is about making a replacement, but with no proof to back up my claim.
What I can add that it will be made in according to the aec-qc100 automotive standard, but I can't really prove anything until I have started working on it. On the other hand, I don't except anything else other than a show of interest as to where I should put the bar on this project.
 
bcsteel

bcsteel

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I’ll get you part numbers. I’m confident with replacing a pig tail. The one thing I think would make it convenient is having it a sealed unit with a plug and play connection from the stock harness.
 
BreckenridgeCruiser

BreckenridgeCruiser

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I don't need one personally, but love the idea. I think @RufusTheDufus was working on something like this a bit ago and may have some input.

Since you are building from new, you may want to think about adding some security features into the device to prevent unauthorized start of the engine. Would be a nice way to prevent theft as our trucks continue to climb in value.
 
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Raggsokk

Raggsokk

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@bcsteel Thanks! I will look into a replacement for the connector that is plug and play. The one on the relay is the easiest to remake, but I also think one need to have the other end available in that case. On my car the female end on the harness is quite badly corroded.
@BreckenridgeCruiser A security feature is a great idea! I have sort of landed on using a small micro-controller inside the relay so adding safety features could be quite easy. Do you have thoughts about what level of security might be needed? One can have everything from quite simply logic to a encrypted key transaction from the desired input interface. I think one of the main points of a security feature in the edic relay must be to deter the easiest attempts, since if you really want to steal the car you can just pop off the shaft from the edic motor.
 
BreckenridgeCruiser

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I was just thinking along the same lines as you. Encrypted key or rfid/USB would be easy and inexpensive. Also, I think a simple shutdown would be ideal as mechanically overriding would be easy, but for those probably not familiar that try to steal using normal methods, disconnecting the signal to the EDIC would work.

For my 1HZ I have a hidden switch for the fuel pump, so the truck can still crank (I thought it might make them think the truck just doesn't start). I also want to add other security like possibly interrupting the starter signal from the starter relay for an added layer. Out of scope for this thread, but having layers definitely helps slow them down when they have to keep finding more issues.
 
Raggsokk

Raggsokk

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Just a small update, I was able to source the original connectors, both the male used on the relay and the female for the harness.
This means that making a fully potted replacement relay that is a true drop-in suddenly becomes much easier and is the route I want to go for.

The connector samples I have received look and feel identical to the original parts used by Toyota, I have attached some photos comparing the old and new part.
I am currently doing a circuit analysis of the original relay design, I will publish an article about it, probably some time during Christmas and continue on making a replacement relay.

Edic m old new crimppin


Edic old neq


Both m f
 
Raggsokk

Raggsokk

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@Darkwing58 Cool, do you know what relay is in your car?

I have so far found out that 4 different Toyota parts are the same type, only difference are voltage and mounting bracket. This is good news for making a universal replacement,
One can also replace the older two relay design, but the easiest way to accomplish compatibility is if one is comfortable with
replacing the harness connector and move one wire in the edic switch housing. I will look further into it.

If any one have more relay part nos and info(A photo of the guts goes a long, long way!) please let me know! It would be great if we can figure out how many different types there are out there early on.

Older two relay design:
28590-56060 (12v)

Newer three relay design:
28590-56090 (12v)
28590-56100 (24v)
28590-57010 (12v)
28590-57020 (24v)
 
Darkwing58

Darkwing58

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@Darkwing58 Cool, do you know what relay is in your car?

I have so far found out that 4 different Toyota parts are the same type, only difference are voltage and mounting bracket. This is good news for making a universal replacement,
One can also replace the older two relay design, but the easiest way to accomplish compatibility is if one is comfortable with
replacing the harness connector and move one wire in the edic switch housing. I will look further into it.

If any one have more relay part nos and info(A photo of the guts goes a long, long way!) please let me know! It would be great if we can figure out how many different types there are out there early on.

Older two relay design:
28590-56060 (12v)

Newer three relay design:
28590-56090 (12v)
28590-56100 (24v)
28590-57010 (12v)
28590-57020 (24v)
I am in Maine for the Christmas, when I get back to Minnesota I’ll check and see which one I have

thanks
 
georgebj60

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Interested as well, for my '87 HJ60. I'll try to post up a picture or part number of my relay.
 
TeamJB

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I have 28590-57020 and 28590-56070 and 28530-56100. If anybody looking for one
 
Raggsokk

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Posted an article about how the 28590-56100 works here: 28590-56100 Relay analysis - Electronics - Kofotronic - https://wiki.kofotronic.com/display/KOF/28590-56100+Relay+analysis
It is a bit of a messy read and could really have used some clean-up and better formatting, but I figured it should be good enough for the purpose.
I apologize in advance for anyone who decide to read it all and if you do, let me know if you spot any errors in the analysis.

If anyone know what the EX pin on the relay is used for, let me know. I have not figured out the purpose of that pin, I have not yet checked the engine manual, but I seem to recall that it was not drawn in last time I checked.
 
izula

izula

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Great article! Now I know why and how my 24v 3B shuts down when I don't goose the throttle a little when starting cold (or if my hand throttle is too low). Thank you!!!
 
N

Neilo

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I would be interested for my 1979 BJ40. Part number for the fuel control relay is

28590-56011

I think your point 3) plug and play with reproduction correct plug would be ideal.

Great idea, cheers, Neil.
 
Raggsokk

Raggsokk

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@izula Thanks for the kind word! Glad you enjoyed it!
@Neilo Perfect, and thanks for the part number, that was a new one on the list, I will see what I can find out.
The samples of the new connectors are verified and worked like a charm, an order is placed on those so we are getting closer.
Got time to work some more on the replacement design over Christmas and some parts for testing will arrive early next week.
I hope that a first iteration can be ready for test some times in March or April, but that will be a bit affected by how busy my day-job gets.
I will keep you guys posted on the progress.
 
Darkwing58

Darkwing58

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@Darkwing58 Cool, do you know what relay is in your car?

I have so far found out that 4 different Toyota parts are the same type, only difference are voltage and mounting bracket. This is good news for making a universal replacement,
One can also replace the older two relay design, but the easiest way to accomplish compatibility is if one is comfortable with
replacing the harness connector and move one wire in the edic switch housing. I will look further into it.

If any one have more relay part nos and info(A photo of the guts goes a long, long way!) please let me know! It would be great if we can figure out how many different types there are out there early on.

Older two relay design:
28590-56060 (12v)

Newer three relay design:
28590-56090 (12v)
28590-56100 (24v)
28590-57010 (12v)
28590-57020 (24v)
Yes it’s the 12v 28590-56090.

would like a sealed connector, I’m planning on making a new wiring harness this year.
 

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