rubronthroad

The starter relay is acting up on my 87, priced it , 165$ these spendy relays are starting to erk me, so I took it apart, looks okay no corrosion, so I plugged it in, had someone turn the key and saw the thing make contact and it fired up, so I guess I will leave this relay in easy reach, just what is the purpose of this thing besides paying for someones dynasty, curious if any keeners know about this, my guess is this thing could be bypassed, anyone ever did that?

Alberta4x

I just bypassed mine tonight, unplugged it and used a regular 30 amp relay from the hardware store. Toyota wired it kind of "wrong" from the factory and there is actually no purpose to having a relay the way it is wired. From the factory, the ignition 12v+ triggers the relay to draw from the ignition 12v+, which is completely useless! (except for eventually needing to replace the $165 relay). Instead, the relay should be triggered by the ignition to draw power directly from the battery, saving the ignition switch from seeing ~20 amps.

To use a normal $5 relay and wire it properly, you will need a 30 amp relay, a short piece of wire, a 30 amp fuse/fuse holder, and probably a few spade connectors and butt connectors. Unplug the factory relay. There should be four wires. Two black wires, a black wire with white stripe, and a black wire with red stripe. The two black wires are both from ignition. Black and white goes to starter. Black and red goes to ground.

Take your new relay, connect terminal #30 to the battery with the 30 amp fuse between the relay and the battery. Connect terminal #85 to either one of the black wires (ignition). Connect terminal #86 to the black and red wire (ground). Connect terminal #87 to the black and white wire (starter). Terminal 87a does not need to be used. I used male spade connectors to connect the new relay to the factory plug.

rubronthroad

Thanks Alberta, so as I understand, I need a 30amp 4blade relay, a thirty amp fuse and holder , as far as the numbers for the terminals, I guess those I can find in the manual,as for connecting terminal #30 to the battery with the inline fuse, thats to the positive terminal?

Alberta4x

It will most likely be a 5 blade relay, you just don't use one of the terminals. The numbers of the terminals will be on the new relay. Yes, #30 goes to the positive terminal on the battery. If you want to keep the factory plug, you may need some spade connectors, or you may want to just splice into the wiring, thats up to you.

RAD4Runner

The Starter relay is not acting up - you already saw that it is in good shape.

Correct.

The starter relay is there for a very important reason. It was was added on 1986 Runners so it will handle the high current (12Amps that I actually measured on mine) required to energize the starter solenoid- that's the thing piggybacked on the starter motor.

1986-1988 starting system is explained here.

Unfortunately, Toyota messed up the wiring, as explained here

IF, and only IF, your wiring is still flawed, even if you replace the stock starter relay with the best relay you can find, if you do not correct the flaw by, that high current to the starter solenoid still passes through the ST1 contacts of the ignition switch, causing tiny arcs each time they make contact and separate, and pitting them, making contact resistance higher, and causing too much voltage drop, so you get less voltage reaching our starter solenoid coil. A healthy battery and charging system will mask this problem. An unhealthy battery and/or charging system will expose it.

This flaw may still exist in later gens (Have you heard of copy and paste? Circuit designers could do that). It would help out others a lot if fellow members could help verify this. Photo below summarizes what to check to verify/rule-out this flaw:


To Troubleshoot next time this happens:
When relay clicks, does solenoid also click? If solenoid does not click/energize measure voltage where spade connector plugs into solenoid. Do this with the solenoid connected. You might have o get creative with a "Y-Connector" so you have access to probe that point.

If you're getting 12VDC there, you know the relay works. IF you get too low a voltage here, you have too much resistance in the circuit. See schematic, rule out flaw and fix it it it exists.

Alberta4x

RAD4Runner, that's why I said to connect terminal #30 of the new relay to the positive battery post. This takes the current off of the ignition switch, and instead uses the new relay in the way that relays are supposed to be used. I already explained this in post #2, please read the thread before posting information that could confuse people.

RAD4Runner

Thanks, Alberta4x.
That's you fix and that's good.
I was replying to OP explaining why the starter relay is there (because he questions its existence) that Toyota wiring has a problem so people would understand what's going on, how to fix it cleanly, without additional parts, and asking other members to help rule out on other gens.

Guys, sorry. ^Post^ edited. I did not mean bypass the relay. I meant "replaced"

Alberta4x,
So you mean to say that you verified that the flaw is also present in the 1987? Thanks for confirming. I'm only sure of it on my 1986 and I have the schematic for the 1988. (Although earlier 1986's do not have the starter relay-- See KidVermicious on T4r.org)

Alberta4x

Yes the problem is present in 87. The wiring problem has been covered several times in different forums. As I explained, the relay was introduced in order to take current off the ignition switch. Toyota wired it in wrong, so it does not take current off the switch like it is supposed to. That is why you should connect the power source wire to the battery like I explained.

The image in post #25 of this thread explains what I am talking about:

https://www.yotatech.com/forums/f131...squeal-160522/

RAD4Runner

Found post 25. Yes, good fix. Somehow when I was troubleshooting mine my searches did not yield this particular thread and no one mentioned it either, so I looked at schematic and found it.

rubronthroad

Thanks guys, I am starting to understand things a bit more, I will clean the contacts on the starting relay, could this wiring flaw be present on a pickup? I will find out if I have it and fix it, Thanks Rad for all your help and thank you Albert, I will stay in touch.

Alberta4x

Easiest way to determine if the wiring flaw is present is to use a 12v tester on the plug. If any of the 4 prongs have power to them, you are fine. If you do not have 12 volts at any of the four prongs, that means that none of them are connected to the battery. I'm pretty sure that this mistake is present on all of the pickups and 4runners, not sure about the newer body style (1989+)

rubronthroad

Thanks Alberta

rubronthroad

So I checked for 12v at the plug for the starter relay and zip on all the poles, engaged key to start position and still zip, does this zerify that the wiring is flawed?

RAD4Runner

In OP you said relay energized, but now you're getting no 12V?

We need to understand exactly how you measured, and this being the newbie section, we must verify . For your convenience pics are right below here:




Did you probe the pins (female) of connector on the harness ?
Did you measure voltage with neg (blk) test probe on battery negative terminal?

• Relay Pin 1: Black-red wire gets ground via clutch safety switch (near clutch pedal) OR clutch safety cancel switch (on dash). To test, you'll need an assistant.
  a) Voltmeter to Volts DC, pos probe on (Pin 3-Black wire), neg probe on blk-red wire.
  b) Have assistant depress clutch AND turn key to "start". You should read 12V.
  c) Release Clutch. Turn clutch safety cancel on, turn key to "start". You should also get 12VDC.
  
• Relay Pin 3: Black wire next to thin black-red wire, is the "control" wire. You should get 12V only when in start position. This 12V will turn on starter relay if thin black/red has continuity to ground. Verify: On relay side connector where THIS and thin black-red wire connects to, there should be a few ohms resistance (relay coil resistance).
  
• Relay Pin 4: Black wire (green line pointing to it) diagonally across thin black-red wire is power for starter solenoid. You should get constant 12V here, even with ignition off.
  IF wiring is flawed:
  a) You only get 12V here when in "start" position, and
  b) There is low resistance (less than a couple of ohms) between this and black wire above.
  Fix by connecting through fused line to battery (like alberta4x did), or to Pin 3 of Fusible Link as in my fix. Moving to pin3 does not require additional fuse because the FL already takes care of that circuit. Either way, you are correctly bypassing the ST1 contacts of IGN switch.
  
• Relay Pin2: Blk wire-wht stripe is relay ouput. Goes to wire connector that plugs into starter solenoid. There should be less than 1 ohm between the this and connector.
  

rubronthroad

Thanks for going into detail about this, so yes I checked the female side of the plugs with the black probe on the neg. batt. term. , and had no reading on the meter, the truck starts up fine, I will go thru the tests you outlined, I will have to wait till my girlfriend is here to assist, in about a week, this is a "project truck" so no biggie.

RAD4Runner

Hmmm... good luck and keep us posted.

Alberta4x

The point is that if there is no reading and you don't get 12v at any of the poles on the connector, the wiring flaw is present. No biggie, if you want to fix the factory flaw, connect #4 to battery.

rubronthroad

I see, I do want to fix it, I will need to clarify which wire to re route, I may as well put in a kill switch, would that be some sort of beefed up toggle? #4 wire you say, isnt the wire I am splicing into smaller #6? Thanks for the help

Alberta4x

#4 wire as in the relay pin #4 at the relay connector. The relay has 4 wires, connect pin #4 (one of the two black wires) to the battery for constant 12v supply. Look at the pictures RAD4Runner posted for reference.

RAD4Runner

rubronthroad, I do not see wire number 6 in the starting circuit, only pin 4 as Alberta4x already said.

If you're talking wire gauge, solenoid coil current is around 14Amps. AWG12 and kill switch (option) to handle that (30Amps to be safe) will be good.

Note that with current wiring, solenoid current takes a very long path. From battery, to dash to ign switch, back to engine comp to relay, then to solenoid. The fix will:
a) Significantly shorten and simplify that run, lowering wire resistance
b) Bypass ignition switch ST1 contact resistance
c) Help extend life of ST1 contacts because now you won't have high current running through them.