Fuse Block Identification

[coronan]

Does anyone know the pinout of the main fuse block?

I want to bypass a burned up pin but am not sure what if it is power coming in or out.
Wire attached to the connector is Blue - Orange.
I could not find blue orange anywhere in the manual from http://toyotavans.org/community/tips/toyo_manual.html

1378

Buler?

My symptoms are no dash lights or tail lights. But the relay clicks. If i wiggle the fuse i can see it arcing out inside the fuse block.

[timsrv]

That burned pin is power-out from your heater relay to the front heater motor. If you check the leads at the blower motor, you will find one wire that's blue with an orange stripe (that's the other end of the same wire that's burned there at that pin). If your blower motor is working at all, with a pin connection looking like that, it won't be for long.

As for the problem of no dash lights/no tail lights, the relay that controls those is the one upper right corner of this same fuse box (other side). The fuse for tail lights is a 15A in the top right fuse position. Wire colors associated with tail lights & dash lights are green & green w/blue stripe. Good luck. Tim

[coronan]

After posting I realized that the fuse socket are numbered on the front and the pins on the back have numbers that correlate.

My blower has been working.
Did the heater pin burn up because the circuit breaker did not open?
new circuit breakers might be in order for insurance.

Here is the exploratory surgery:

The image in my OP shows 4 round black dots in the corners of the block. They are plastic rivets. Drill them gently not to go to deep. Just drill off the black.
Then gently pry the 8 white locking tabs from the black housing.
Then you get this.
1384
WARNING: take pictures as you go because, sh*t gets confusing and thing fall out. Pieces will fit into the wrong place but the assembly will only go together one way.

The whole thing splits into 3 layers

1386

I cleaned everything with battery cleaner and compressed air and made sure there were no more burnt pins.

1387
Here is the carnage.
1385

I tried several times to clean it and re-tin it with solder but not luck on getting the solder to stick. So i ended up just cleaning it with a wire tooth brush.

While I was in there I put a drop of solder on all the female sockets seen in the bottom of the picture as insurance. There are about 10.

I was able to replace the female side of the burnt pin with a standard blue quick connect. I crimped and soldered in a short section of new wire. Old wire was pretty rigid from all the heat. Sorry no pics as it was almost midnight.

I also packed all sockets with conductive grease to keep dust out and improve conductivity.

[timsrv]

Not necessarily anything wrong with your blower motor or the circuit breaker. For circuits with higher constant current this type of damage isn't unusual. It all starts with a slightly loose connection. When things are new and shiny they are very conductive & even loose connections do their job. As time goes on and things age metal parts tarnish and conductivity is diminished. The result is resistance to electrical flow. Resistance creates heat & heat creates more resistance. This doesn't mean current goes up (therefor circuit breakers and/or fuses will not protect against this). At some point the resistance vs current flow becomes too much and arcing occurs. Once arcing starts the heat gets intense and the resistance goes infinite (circuit opens).

As a tech I see this sort of problem on a regular basis. Very rarely is there any fault with the circuit other than the burned connection itself (was probably a little loose at time of manufacture and simply took this long to get this bad). When this occurs it's always best to replace both female & male connectors or completely bypass the connection with a jumper wire. In this case you did the best you could with what you had. For this type of low voltage circuit I would consider this acceptable. I would however crush the female connector slightly so it takes more force than normal to push it on that pin (to make sure it's very tight). I would also cut the wire back to a point where there's no heat damage (soft & flexible). If that makes it too short then extend it with the same or heavier gauge wire. When using solderless connectors always use quality connectors (I like nylon insulated) and crimp with a quality crimper. Klein or other professional grade is highly recommended. Tim

[drew]

Been searching for a pinout diagram for the connectors at the rear of the fuse box...
Curious what took the heat here and got fried...
5178
5179

[drew]

Maybe it is the rear wiper connector...

5182

The color of the wire for that fried terminal is light blue with orange stripe (L-O). Noticed a L-O on the wiring diagram for rear wiper, but also for heater. So maybe it powers both? Newb I know!

5181
5183

[drew]

Decided to take the fuse panel apart layer by layer, cleaned all pieces with alcohol/wire brush, and dielectric greased all connections.

Here are reference pictures of the circuitry.

Layer 1
5187
Layer 2
5190
Layer 3
5186
Layer 4
5189

[timsrv]

After burning 3 different fuse panels over the years, I finally built a separate circuit for the heater fan. I used a standard Bosch relay and a 30A self resetting circuit breaker. Since doing that my fan has worked flawlessly. The spade connector on the fuse block is the weak link. Tim

[whatvan]

I had the blower motor problem. Replaced that and the resistor. When the new blower still wasn't working on High, i repeated my "jiggle test" of the wires behind the fuse block. That seemed to be the culprit. When jiggled to the correct spot, I would get heat in all fan speeds.

Once all the wiring harnesses were disconnected and I could get a good look at the rear of the fuse block, there doesn't appear to be any noticeable damage, as on the fuse block pictured above.

I removed the blue w/orange stripe wire from the harness it was located in, pinched together the female pin a bit tighter, reinserted to the harness, lightly sanded the male end from the fuse block, cleaned with contact cleaner, reconnected all necessary harnesses to the fuse block. tried testing the heater by turning the van to the "on" position with the heat on high... nothing. Jiggle, jiggle... still nothing.

I tested the relay thinking I may have damaged it jostling things around. I do not get continuity between terminals 1 and 3, or 2 and 4 when just looking for relay continuity. hooked up to 12V power (terminal 1+, terminal 3-), it clicks and i get continuity between terminals 2 and 4. Thinking this relay may be bad based on what I've read in the service manual about not having continuity between 1 and 3, I checked the rear heater relay and got the same results. I'm kind of confused by these results. In my head, if the relay is clicking when power is applied, and there's continuity between 2 and 4, it seems as though the relay would be working. but I only have a rudimentary understanding of such things.

I'm kind of stumped right now. I have to go to work soon so I'm going to pick up a new female pin connector for the blue w/orange stripe wire. I may also try to see if the autoparts store has a relay I can buy, no idea if that's an option.

What am I missing? I really am apprehensive to tear apart the fuse block (as was done earlier in this post) to replace the male end of the connection. with the condition it appears to be in, no burning, looking no different from any of the other male pins on the back, it seems unnecessary. because I live in the van I am borrowing a friends vehicle to go to work, using his garage to do the work, and crashing his couch in the meantime. any quick response is greatly appreciated.

Thanks, Dave

(if this should have been in one of the heater posts, I apologize, but was using this post for reference to get to this situation)

[timsrv]

did you try resetting the fan breakers? They're the round devices on the front of the fuse panel. There's a little hole to push a paperclip or other small point into. Doing so should reset. Tim

[whatvan]

Thanks Tim,

I knew I left something out of my post in my haste to get to work.

I did try resetting the breaker in my process. But since you suggested it, and I left it out, I figured I would hook everything up again this morning and try resetting the breaker for good measure. It wasn't tripped, with everything hooked up and the key in the "on" position, I still got nothing. However, I must have held my tongue in the right place for a second cause the heater kicked on briefly when I tried to get the fuse block back to its original location.

So it's gotta be some sort of lose connection.

Is there any chance there could be a lose connection somewhere else in this, or another harness that would be affecting the heater blower? Somewhere else nearby in this circuit?

I've tried hooking up just the blue/orange stripe wire, to its male pin on the fuse block, without the rest of it's harness and got nothing. I assumed there's another part to that circuit located in the harness which is why I got the result I did.

Am I correct?

When the harness (with the blue/orange stripe wire included) is plugged in to the back of the fuse block, I'm assuming my alterations to the female pin are sufficient, but I'm not sure how to definitively prove this. The way the harness is set up, I can't see any way the connection isn't being made between this wire harness and the fuse block.

What got me into all of this in the first place was my heater blower would turn off indefinitely when I hit a bump. Until I hit another bump just the right way, then it would come back on. No rhyme or reason to how or when. Again, this steers me towards a lose connection.

So do I just keep plugging away trying to remedy this connection or do I start looking for another lose connection that could be a problem.

Van has little over 170,000 miles right now.

I'm gonna be working on this issue all day till i figure it out :wall:. Once again, any and all help is greatly appreciated.

Thanks, Dave

[timsrv]

Before power is delivered to the blower motor it goes through the fuse block, a breaker, a relay, and the blower resister. Among these stops there are several connections (all potentially a problem). IMO the fuse block is the weak link, but any of things can create an issue. After dealing with this several times I pulled my fan circuit off the fuse box and ran power from the battery, then through a Bosch relay (triggered by the ignition switch), then through a STD 30A self resetting circuit breaker. I'm still using the stock blower resister. Since doing that (about 2 years ago) I've not had another problem (knock on wood). Tim

PS: Here's another thread with links to others: http://www.toyotavantech.com/forum/showthread.php?4832-What-is-this

[whatvan]

Well, I like to fix things one time. So if there's a fix that can keep me from doing this again for a while, I'm all in.

I'm not to apprehensive with electrical work. I was raised to be an electrician, so I understand the importance of good connections, proper wiring practices, etc. And, like many ill advised teenage youth, spent a lot of time and money playing with fancy electronics in automobiles, which gave me a fundamental understanding of wiring practices there as well.

I've spent some time trying to find a "how to" thread for the rewiring of this circuit to avoid the fuse block, with no luck. In the spirit of learning to know and not forget, I figured it a better use of my time to try and figure it out on my own. I might have been wrong.

I can, to some degree understand the wiring diagram I've tried to attach to this thread (better than I do uploading photos), and have a general sense of how power travels around in this circuit. I, however, do not understand what everything is (like the "ac amplifier" that the light blue/red stripe wire [L-R] connects to from the heater blower relay) and it's role in this circuit.

So without hesitation I'm always looking for someone with more experience to validate my best guesses. Here's what I think I need to do to circumvent the fuse block:

1. positive from battery to 30A self resetting breaker.
2. positive from breaker to Bosch relay open switch side
3. positive from bosch relay closed switch side to heater blower
a.) should I remove the light blue/orange stripe (L-O) wire from the harness and splice into it?
4. Then I will need to use the yellow/black stripe (Y-B) wire from heater blower switch to connect to one side of the new Bosch relay
a.) I only see one Y-B wire going into the fuse block. It connects on the back of the fuse block at male pin position 15 and is part
of the harness directly next to the one with the commonly burned L-O wire. Is this the correct wire to tap into?
b.) If this is the correct wire to tap into, remove from harness, create splice?
5. The remaining position on the Heater Relay in the diagram is shown connecting to the "ac amplifier" using a light blue/red stripe
wire (L-R)
a.) Should I connect from the ignition switch to this final position on the new Bosch relay?
b.) Where would the best spot to tap into the ignition switch be?
c.) I only see one L-R wire going into the fuse block. It connects on the back of the fuse block at male pin position 40 and is part
of the harness directly next to the one with the commonly burned out L-O wire. While I don't know what the ac amplifier is,
it's my instinct to keep things wired as close to the original way as they were. However, if this is another potential problem
spot I would gladly bypass it. (My ac doesn't work and I don't care if it ever does again.)

Am I close, way off?

I'm currently on day 3 of having Whatvan torn apart in my friends garage, sleeping on his couch (cause the van is home) and annoying his amazingly patient girlfriend. They are doing a big holiday at their place so the van has to be put back together by 2:00pm tomorrow, working or not. I'm going to try and get a breaker and relay at orielly's immediately. If they don't have the name brand parts Tim mentioned, but something close, I'm going to go with it for now and replace when there's more time.

Thanks again, Dave

[whatvan]

*Update

As I was putting things things back together, I tried jiggling the wires behind the fuse box again in hopes I could find a temporary solution while I find time and another garage to work in.

By coincidence I had the fuse cover off and accidentally bumped a couple of fuses. This caused the heater blower to kick on temporarily. After jostling the 15A fuse labeled "AC" I removed the fuse and noticed the female pins in the fuse block were damaged. It was on the front end that I had the loose connection.

I sacrificed the end of a metal zip tie and fitted it over the ends of the fuse pins to take up the extra space.

I'll use this as a temporary solution through the holiday, and get back to the garage to run a new breaker and relay.

[timsrv]

Yeah, somebody's hammered that fuse box. They probably used "fuse taps" at one point or another on that circuit and spread the conductors inside the box. Once that happens that fuse slot is unreliable.

I can't remember exactly how I built my circuit (2 years ago), but I pretty much copied the way Toyota did it except with aftermarket components (external to the fuse box). Sounds like you got a good temp fix, but that fuse slot will likely give you more headaches. I would probably start looking for a good used fuse box. Tim

[s_e_a_n_s]

(reviving an old thread... maybe this is a no-no).

I have a fuse box and connector that look identical to the 1st pictures in this thread - melted at blower relay post/connection. It looks like finding a replacement fusebox (or 'BLOCK ASSEMBLY' as Toyota calls them) will be a challenge. I assume finding a replacement connector is the same.

I disassembled the fusebox (same as shown in the thread) and after cleaning up it doesn't too bad.
That is to say: the rest of it looks great and one post is floating in a melted hole.

Questions:
* Any suggestion for filler for the melted area on fusebox side? Was thinking epoxy or RTV. Mostly just want to keep things from moving around.
* Anyone attempt to replace the plastic rivets? or did you rely on the tabs? I was considering drilling all the way through the old plastic posts (out the front) and replacing w/ plastic or aluminum pop-rivets or zip-ties
* Any idea why this particular connector is problematic? Others connections, like main c/b, carry more current. Is it undersized or prone to contamination?

Thanks.

[timsrv]

Opening & adding to old threads is what we want........keeps all like information together. Thank you for not starting a new thread :). This is a common problem with circuits that carry heavy loads for long periods of time. Sure, you can clean it up/repair and get a little more life out of it, but it's never going to be as strong as it once was and you will almost certainly need to revisit this again and again. Since we cannot get new parts, the best alternative is to take the load off the circuit. This can be accomplished by using the weak original circuit to run a relay (Bosch works good), then run a new wire (12 ga or bigger) from your battery to carry the load. I used 10 ga wire and a 30A breaker on my power wire. If you use a lesser wire, just make sure the breaker (or fuse) is sized correctly just in case there's ever a short. I've been running mine for over 5 years this way with zero problem. Tim

Maximum fuse/breaker size determined by wire size:

14 ga wire = 15A
12 ga wire = 20A
10 ga wire = 30A

[s_e_a_n_s]

Thanks Tim.

Moving the connection out of the fuse panel is probably the best approach, and it has the added benefit of being isolated so less of chance of melting important/difficult to replace parts if it fails again. I also agree that once the pin is burned the job of making and maintaining a perfect connection becomes a lot harder.

However, it seems like the only problem is with the connection at that one pin - in theory if you can keep a good connection at that pin it should work just fine. The rest of the circuit - relay/ breaker / connections are all okay.

I'm sure you understand this better than me, so pardon the man-splainin', I just can't help myself... The issue is the connection at that pin develops a little bit of resistance. Add current and that resistance produces heat which, slowly at first, makes the connection worse... which generates more heat... which makes the connection worse, which generates more heat.... until at some point it turns into a toaster.

The math is actually pretty discouraging. I'm not sure of the actual blower motor draw on high - lets says it's 25A. If the connection develops .01-ohm resistance... almost nothing:
V = IR = (25A * .01-ohm) = .25 Volt drop across the connection
W = VA (.25V * 25A ) = 6.25 Watts (!!)

6-watts is a huge amount of heat to dissipate (take a look at 5-watt resistors - they are 3/4-inch ceramic blocks). And that's only w/ .01-ohms, .02-ohms and it doubles. The plastic doesn't stand a chance.

So... I gotta figure out if there is something I can do create and maintain a near perfect connection at that (now degraded) pin. If so, it should be fine. If not, using the current output to power a remote relay (+ circuit breaker) somewhere else seems like the best and only option.

Thanks again.
-Sean.

[timsrv]

I don't remember the exact draw on that circuit, but I'm guessing it's ~10 amps. It's not so much the load, but the fact that fans tend to run a lot. It's the constant stress that eventually causes that weak point to fail. At one point I had 5 or 6 extra fuse blocks and all looked good. When I got down to 2 or 3 spares I reduced the load using the relay method. If you don't want to run a new wire all the way to the battery, there's a pretty good sized wire supplying power to the fuse block (~8 ga if I remember right). On one of my vans I just took the relay load power from that and used the old burnt pin to energize the relay coil, and it's been working fine. Tim

[s_e_a_n_s]

Thanks again.

I was eyeing the big white wire coming in as a source for power. I don't really want to splice it - tying in at the connector/crimp would be convenient (if I could find a suitable replacement F spade that would work in the connector.

Despite the blower motor being on a 30A C/B the wire that feeds the front blower motor is only 12-gauge ('L-O', light blue + orange). With the insulation on it'll slip right through my 10-gauge wire strippers.

For the short term I'm planning on putting a 2" pigtail off the burnt pin - This gets me rolling again and gives an easy path to upgrade to external relay, maybe without having to remove the fuse box again.

Question: Do you know it's easy/possible to find uncrimped female spade connectors that are compatible with the toyota wiring harness connectors?

[timsrv]

Question: Do you know it's easy/possible to find uncrimped female spade connectors that are compatible with the toyota wiring harness connectors?

It's possible, but there wouldn't be a Toyota part number or any way to verify (other than ordering std stuff and then checking to see if it interchanges). Back when these vans were still in the yards I would grab the fuse boxes out of them. I brought my wire shears and took as much wire as I could easily get along with the connectors. When I need something like that now I just take the connector and attached piece of wire, then butt connect that into my harness.

I'm betting you could find the right gauge wire with the right spade on it in almost any Toyota from the 80's & 90's. Just go to a salvage yard with a pair of dykes and snip snip away. :wnk: Tim