atcfixer

iTrader: (1)

Thanks to RAD4Runner for pointing out the design flaw in these trucks for the starter circuit. To keep this simple, the power to turn the starter solenoid on runs directly through the ignition switch with the starter relay in the middle (effectively doing nothing to protect the ignition switch). I have to do some testing, but I'm pretty 95% sure I can make a pretty simple and cheap sub harness to plug into the stock relay connector and fix the wiring design. Side effect of this is the ignition switch is actually protected (low amp draw, no contact burning any more), and the other side effect is I can make the harness wire to a completely different and more available relay. First one that pops in my mind is the ford starter relay that's used on effectively every ford in the 90's and are commonly used for high amp circuits like the glow plugs on a powerstroke (180amp for up to 3 mins). This would be a massive upgrade over the stock design, and I'd think it would be much cheaper option than replacing the stock starter relay with a used oem starter relay.

Does anyone have interest in this kind of product? I could use someone to test this. I have an 86 pickup to test on. I have wire diagram books for 86, 87, 89 4runner, and 90+. I'm targeting the 86 style first (assuming it's 84-88 pickup and 84-89 4runner for this relay connector/location), but I'll have to dig in the wire diagrams to validate what years are covered.

FYI, 1992 and newer trucks & 4runners have the issue fixed.

Everything will be plug and play and I should be able to use the factory mounting location for the new relay. The kit should be reasonable priced, the harness/adapter I should be able to make for $50 or less, the brand new ford relay (called solenoid) is as cheap as $11 from China, or about $60 for Ford OEM (Motorcraft).

atcfixer

iTrader: (1)

Here's the circuit design, incorrect vs correct (91 vs 92 pickup in these examples).

Incorrect:



And corrected (92 pickup, forgot to label that in the image):



Based on fuse ratings, the incorrect style functions behind a 40 amp fuse, so a 40 amp fuse + relay rated for 40+ amps should be good. I suspect this will also prolong starter solenoid life as the wiring is more direct and less switching points for voltage drops.


Anyway, let me know if you're interested, or want to test the product. Feedback of course is welcomed too.

atcfixer

iTrader: (1)

I got linked this thread on the subject, it has a lot of info, this is the same goal I'm trying to do but with a ready made plug and play kit. For the DIYers, it's not too hard to build. There's no real spec on the starter solenoid, so can't really say if 30amp is large enough or not, but if no one has had blown fuses, it should be fine. I probably should get an amp load test on the solenoid to get an idea what the real power draw looks like. I'm sure it's over 10 amps, guessing around 20-25 amps.

https://www.yotatech.com/forums/f116...runner-307493/

atcfixer

iTrader: (1)

Dang... I checked my vintage connectors, I don't have the 4 pin version on hand, only 2 and 3 pin. I'll have to order them and wait for the package from Japan. Probably should order some 1 pins for that connector series too.