7.3 IDI Banks Turbo - E40D in limp mode - No Tach - Help Identify Relays

Drove truck home after running errands for a couple of hours, truck was fine, no warning or anything of something going on with trans. Left house, starting driving and realized transmission was not running right. Then noticed tach was not working, and so it began. Limped home, literally and started looking at things. Determined it was limp mode, started feeling a little better, and then tried to figure out why.

Luckily, had a big visual cue that the tach was not working and hit on some searches for that. Determined was relays so went down to the truch and started looking at things, after I looked at where they were, I am knew at this. With my son watching the tach, started jiggling/tapping in wires/relays and he shouts out tach is working. So, electrical issue seems to be the key. Now, neither of the relays was in the holder, thin black rectangle behind the reservoirs on the driver side projecting into the engine compartment, next to the coffee can. I dont know which is which, they have keyed slots so only go in one way, head down to napa. They finally find a match for one, said ECC/TECA but it is square.

Attached are pictures of the two of them, showing the, keyed slots for the pigtails. I thought I should have 3 relays, I believe I have the factory tow, but perhaps it was centurion installed. I found a note that I might need to get new pigtails too, design change. The ones in there are now are from Ford. They and the pigtails are corroded pretty bad.



Thanks for help.

David

The TECA relay has the following wires: yellow (battery power), solid red (TECA and solenoid pack feeds), red with light-green stripe (ignition key-on trigger for relay), and black (ground for relay).

The tow package relay has the following wires: yellow (battery power), white with red stripe (trailer running lights feed), brown (relay trigger tied into truck's own running lights), and black (relay ground).

These are the only two underhood relays that you'll find on a diesel '87-'91 truck. Any parts store should have universal Ford relays, they are 5-pin relays with the locating slots configured in such a manner that one relay can fit any of the (IIRC) three different connectors Ford used over the years. Or you can install standard Bosch-style (aka ice-cube) relay connectors and run relays that are found on just about any more modern vehicle. Maybe that is what the updated pigtails are, I'm not sure, I converted our IDI truck to full Bosch-style with relay boxes and such so idk what's out there as "factory" replacements...

Thanks for the info. I like the idea of going to newer relay cubes since I will need to rewire the pigtails anyway ... can I just go to parts yard and grab any relay holder box that has enough slots and wire it in or?

Yup, that's what I did, on a grand scale Ford actually put some real nice 2-relay boxes in some mid-'90s vehicles, you have two options there:

1) for two 40-amp relays, look for a '92-'96 F-series truck with factory tow-package. Relay box will be in the driver-side rear corner of the engine bay, on the inner fender between the power distribution center (huge fuse box) and the firewall.

2) for one 40-amp relay and one 70-amp relay, look for a '92-'97 (or possibly even newer) big passenger car with factory ABS. Relay box will be in the passenger-side front corner of the engine bay, on the inner fender right behind the battery and the power distribution center (huge box).

So try and get the truck moving again, sprayed it all down with crc electrical cleaner, seemed to take some residue off but did not actually remove the corrosion.

How do you all get the contacts cleaned up? Different compound? Sandpaper?

Thanks,

David

You can try getting some sandpaper in there, not sure how effective that will be. The CRC stuff is so-so, not very effective on damaged surfaces. You can try unpinning the connector and pulling the wires one by one and soaking their metal ends in some weak acid, forgot what kind tho, muriatic maybe?

i don't think id mess with that.id follow the advice given by ripping those out and heading to the local yard for anything decent you find under any hood really for some relay boxes.id just snip the wires and wire up new universal harness or just crimp on connectors to fit the new relay before trying to re-use those at this point.

Might try a tooth brush and some weak battery acid. Wear eye protection. Flush clean with water and baking soda. Then some grease to prevent corrosion again. Battery acid is around 6% sulfuric acid. Its far more corrosive than 98% sulfuric acid.

I am new to some (all) of this, and do not like the acid route, think to easy for me to have something go wrong. Heading to local pick-a-part.

David

Ok. Didn't have much selection, but ended up with I believe the 40 70. Since the original two were just hanging down, I do not know which one is which, which one takes 40 which one take 70?

Yup, that's the 40/70. Got a cap to go with it? the grey one is the 70, the black one is the 40. On Ford boxes of that style (there are larger ones as well with 4 relays, not just two) the tall slot is always the 70-amp relay. If you pull the relays off you'll know the difference immediately, the 40-amp one has your standard 1/4" terminals all around, while the 70-amp one has 1/4" terminals for the trigger circuit and IIRC 3/8" for the loads. So I suppose you'll wanna know how to wire them up now, right?

So, I might need help, but here is what I am planning on doing. Since they should have the same number/type of wires, I was going to cut off existing pigtail and join to the new box, wire by wire. This works to an extent except that one of the existing relays in my truck I think has 4 terminals and not five if I remember right. It is middle of night here and not going to walk out and check right now.

I will take a look in the morning and see if it seems to make sense. While everything seems to take forever as I am learning, glad to do it and glad for the help.

David

OK. Have to admit, most everything I found was for horn, headlights or fuel relay updates, so taking a shot at it, this is what I have for TECA

pin 30 - yellow (battery power)
pin 87 - solid red (feed to TECA and solenoid)
pin 86 - red with light-green stripe
pin 85 - ground
pin 87a is ignored

For the tow relay:
pin 30 - yellow (battery power)
pin 87 - white with red (feed to lights)
pin 86 - brown
pin 85 - ground
pin 87a is ignored

This seem right?

Yeah that should do it. Keep in mind the relay box may actually have wires and connectors that match pins #87a, so make sure you find which ones they are and cap them off properly. How do you plan on finding out which wire for the box goes to which terminal on which relay, measure them all? Well you probably already figured that the really fat ones are the power and load for the 70-amp relay. If I have a spare box laying around I can open it and tell you which color wire matches what pin # on which relay, I'll have to check tomorrow...

Progress Report - Question on Wires

Here is my original bracket:


Here is where I am fitting a bracket I made to hold the relay box:


Here is a test fit of the new relay box, fits pretty well.



Now, I would like to clarify somethings before I cut and solder up the new box.
1) My Tow relay has no white with red, but it does have a brown with white, or maybe that is dark gray with white



2) My TECA has two yellow wires going to the same connector. Assume this is ok???


3) I read online that it really doesnt matter which way the wires the signal wires are connected, but not so for the load wires to the battery. Is this true or do I need to worry about matching to the original relays exactly?