slodat Posted February 6, 2007 Report Share Posted February 6, 2007 I have done this simple mod to every Datto I own. Reason is the starter solenoid power goes through the ignition switch's start contacts. This circuit drops some of the much needed battery voltage, especially in 30+ year old Dattos. This can ultimately mean there is not sufficient voltage to pull the starter solenoid all the way in and make contact. Pick up a Bosch style 30/40a 12v relay. They are everywhere and are very cheap if you know where to buy them. I bought a 10 pack with wiring harnesses for ~$25 on eBay. Wiring: 30 - 12v from battery (fuse this line) 87 - starter solenoid terminal 85 - original wire from starter solenoid terminal 86 - ground Now, when you turn the ignition switch to the start position, the coil in the relay is energized from the ignition switch. This connects the starter solenoid terminal directly to full battery voltage. 1 Quote Link to comment
Bleach Posted February 6, 2007 Report Share Posted February 6, 2007 interrupt the '85' wire from the starter solenoid and run it to a hidden toggle switch. This will act as a starter kill switch. Also, install an alarm. :D 1 Quote Link to comment
71-521 Posted February 6, 2007 Report Share Posted February 6, 2007 Thanks for the how-to... This can also be used for the headlight conversion as well as other things you want to straight wire around the switch, like heater blower and wipers!:) best alarm devised yet: trunk monkey!:rolleyes: Yours must have had a hangover that day bleach! We told you not to let it drink beer!:D 1 Quote Link to comment
slodat Posted February 6, 2007 Author Report Share Posted February 6, 2007 That is true, relays have a lot of uses in our old Dattos. Think of it as an electrically controlled switch. One of the best improvements I've made to my 510 was replacing the stock headlight relay with Bosch relays on both high and low beams. They are also great on the horn, dome light, you get the idea. 1 Quote Link to comment
djlotus Posted March 30, 2008 Report Share Posted March 30, 2008 Figure I'd share some info I found out the other day from a friend of mine. The engine bay fusebox in Intrepids have a shit load of relays in them. Only downside is that they don't have any mounting tabs. Not that big a deal to me tho, from one Intrepid I walked out with about 10 relays. Also, is there a comprehensive list about Datsuns and relays? I know of this one, and the headlight one. I don't much know about any of the other ones. 1 Quote Link to comment
datzenmike Posted March 30, 2008 Report Share Posted March 30, 2008 The 720s have a 15 fuse box with at least two relays (3 in US) clipped to it, and two more above the pass kick panel for auto choke and electric fuel pump. 1 Quote Link to comment
freaky510 Posted November 1, 2008 Report Share Posted November 1, 2008 so i googled Bosch style 30/40a 12v relay and after all for sale shit . was the ratsun forum link. now thats cool!!! also this is great thank you for posting this .I have had a problem startig my dime sometimes it took 8or9 trys :blink:before it would kick now it starts like a new car :eek: 1 Quote Link to comment
Bleach Posted November 1, 2008 Report Share Posted November 1, 2008 now it starts like a new car :eek: that's freaky! :blink: 1 Quote Link to comment
banzai510(hainz) Posted November 3, 2008 Report Share Posted November 3, 2008 hotstartrelay 1 Quote Link to comment
drummingpariah Posted February 18, 2009 Report Share Posted February 18, 2009 I just ordered a 10-pack off ebay for $25, including shipping and wire leads. The seller apparently stocks up on them here: http://myworld.ebay.com/ebaymotors/installerparts I'll let you know how long it takes for them to arrive. 1 Quote Link to comment
ariascarlos1990 Posted February 19, 2009 Report Share Posted February 19, 2009 any pictures on how to do this? seems easy but, I'm an idiot when it comes to electrical.... Thanks 1 Quote Link to comment
nukeday Posted February 19, 2009 Report Share Posted February 19, 2009 I'm going to do this on my truck, and leave the 30A fuse out. It's not ready to start, but I want to test the rest of the electrics. :D 1 Quote Link to comment
Llittle_Llama Posted February 19, 2009 Report Share Posted February 19, 2009 nice writeup slodat, I will be doing this now when I redo the headlight wiring I did in Alabama :D 1 Quote Link to comment
Zeusimo Posted October 13, 2011 Report Share Posted October 13, 2011 What Gauge Wires Would Be Used Here? :unsure: 1 Quote Link to comment
izzo Posted October 13, 2011 Report Share Posted October 13, 2011 i think 14 gauge would be the way to go. 1 Quote Link to comment
elmerfudpucker Posted October 13, 2011 Report Share Posted October 13, 2011 What Gauge Wires Would Be Used Here? :unsure: Great write up and one of these days someone is gonna steal your shift keys! :lol: 2 Quote Link to comment
ninjabortion Posted October 13, 2011 Report Share Posted October 13, 2011 running from the factory ignition switch you can just reuse the factory wiring and match that size, if it can power a starter it can engage a relay no problem. on the other side i would just go bigger than whatever the stock junk was and call it good, unless you want to get fancy and do the math :P http://www.powerstream.com/Wire_Size.htm 1 Quote Link to comment
zerow Posted October 13, 2011 Report Share Posted October 13, 2011 I ran a 12 gauge wire from the battery to the relay and from the relay to the solenoid. 14 gauge wire for all the trigger wires. I even wired it through my starter interlock switch so it only makes contact in Park and Neutral. Other than a solenoid issue (that I knew about beforehand...) it works great. No second guessing the voltage at my solenoid (which I recommend everyone check prior to install, just to have a baseline). Mine was 9.9 volts at the solenoid in START prior to install...! 1 Quote Link to comment
az_rat210 Posted December 9, 2011 Report Share Posted December 9, 2011 Here is a link I often look at for wiring Relays. Relay Wiring The use of a quenching diode is a good idea to prevent feedback in the curcuit after the circuit is shut off. 2 Quote Link to comment
d510addict Posted June 25, 2013 Report Share Posted June 25, 2013 interrupt the '85' wire from the starter solenoid and run it to a hidden toggle switch. This will act as a starter kill switch. Also, install an alarm. Interupt the wire before or after the fuse? 1 Quote Link to comment
Tristin Posted June 25, 2013 Report Share Posted June 25, 2013 Interupt the wire before or after the fuse? It doesnt matter as long as the switch goes back to the same spot in the circuit. There is nothing to "blow" when using a toggle switch so there doesnt need to be a fuse... if you interrupt the circuit prior to the fuse, when you wire in the switch it needs to be completed prior to the fuse. If you interrupt after the fuse, you need to complete it after the fuse. You wouldnt want to bypass the fuse when your toggle switch circuit is closed. 1 Quote Link to comment
d510addict Posted June 26, 2013 Report Share Posted June 26, 2013 Sweet, Ive had to push start my truck some days because the starter refuses to engage. Hopefully I can get this relay in without a hitch. 1 Quote Link to comment
DaBlist Posted July 23, 2013 Report Share Posted July 23, 2013 I like the smaller modern relay you show. I have done this using a Ford style starter relay and have bought several rigs that already had it done with a Ford type. They worked well but larger and heavier than the ones you show 1 Quote Link to comment
datO))) Posted February 11, 2015 Report Share Posted February 11, 2015 I hooked my relay up today . It did not work. Mine is the Pico brand. I switched #87 to 87A and it turned over but would not Turn off the solinoid. According to my diagram, 30= battery. This is going to a 30a fuse on the fuse block. 85= ground 86= key ( ignition) going from relay to the Terminal were the starter would go. 87/87A = starter. What I'm I not understanding. #87 would just Click while 87A would turn over but not shut off the starter after Ignition fire. 1 Quote Link to comment
DanielC Posted February 11, 2015 Report Share Posted February 11, 2015 It should not necessary to add a relay to make the starter solenoid engage. There is a problem with the wiring somewhere else, and this "hot start" relay is just masking the real problem. If you connect a wire to the 1/4 spade terminal on the starter, with good battery cables, touching that wire to the positive battery terminal should make the starter engage, and the starter should disengage as soon as you remove the wire from the battery terminal. EVERY time. Check that first. As far as the starter knows, the only thing the ignition switch does is connect the 1/4 spade terminal to battery positive. Lets follow the power the starter solenoid normally gets, from the battery positive. Power from the positive battery terminal goes to the fuse block. Depending on the year of 521, three or four fuses are always hot. There is a white wire from the always hot side of the fuse box, to the ignition switch. This white wire after the fuse box goes into the engine room wiring harness, and in to the cab, behind the glove box. There are a bunch of multi pin connectors there. The white wire then continues to the key switch, and the connector, or plug on the key switch. When the key is in crank position, the switch passes power to other wires, including the black wire with a yellow stripe. This wire goes back to the connectors behind the glove box, and continues on a black wire with a yellow stripe. That wire goes to the 1/4 spade terminal on the starter. If the connectors behind the glove box have ever had water condense on them, in the last 45 years of the truck living in Oregon, there is a good possibility the connector contacts may have some corrosion on them and are not really making good contact. A poor connection anywhere else in the chain can also reduce the current that can get to the starter solenoid. If the connections and wiring that a stock Datsun uses to engage the starter needs the "hot Start relay" chances are it will be a short time before the connection continues to deteriorate to the point it will not even make the relay switch on. On a cube relay, pin 86 is coil positive, pin 85 is coil negative. Pin 30 is usually where load, or switched fused power is applied to the relay. Pin 87 and pin 87A ARE different. Pin 30 is connected to pin 87A when there is no power on the coil of the relay. This is called "Normally Closed" or NC connection. Pin 87 only connects to pin 30 when power is applied to pin 86, and pin 85 is grounded. Pin 87 is called the Normally Open, or NO connection. 2 2 Quote Link to comment
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