ArdWrknTrk Posted January 14, 2020 Share Posted January 14, 2020 And now for a potential modification of the starter relay plans. I found that I have the box below, which has four relays. Three are the standard Bosch 40 amp relays, but the fourth is a 70 amp job with the big terminals, as shown on the spare relay below the box. So, instead of the fender-mounted starter relay, how 'bout a stud to take the charge cable from the alternator, the battery cable, the fuselinks to the Bullnose wiring, and the cable running across the radiator support to the PDB. And then use this box for two headlight relays, the blower relay, and the 70 amp relay to pull in the starter. The downside is that this box doesn't have any positions for fuses and I need a fuse for the headlights. Having said that I do have an auto-reset circuit breaker that I used previously on the headlight wiring harness and it would work just fine, although not as elegant as a slot in the box. What'cha think? Since I'm using a 40A relay to activate my starter solenoid, I can't see the need for 70. I'd probably use 87a for low and 87 for high. Why would you need two? My, that's a big blade on 30! Maybe it is used for electric fans? Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 14, 2020 Author Share Posted January 14, 2020 Since I'm using a 40A relay to activate my starter solenoid, I can't see the need for 70. I'd probably use 87a for low and 87 for high. Why would you need two? My, that's a big blade on 30! Maybe it is used for electric fans? Yes, it is a BIG blade, on both 30 and 87. And while 40 amps is obviously adequate, there no downside to 70 amps of capacity. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 14, 2020 Author Share Posted January 14, 2020 Since I'm using a 40A relay to activate my starter solenoid, I can't see the need for 70. I'd probably use 87a for low and 87 for high. Why would you need two? My, that's a big blade on 30! Maybe it is used for electric fans? Missed the bit about 87 and 87a. Need one relay to put power to that one. Or, one each for high and low. How do you do it? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted January 14, 2020 Share Posted January 14, 2020 Yes, it is a BIG blade, on both 30 and 87. And while 40 amps is obviously adequate, there no downside to 70 amps of capacity. As said above, you'll need a cable capable of 70A just to drive the solenoid of the starter. That seems a bit absurd to me if the solenoid only requires 13A to hold. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted January 14, 2020 Share Posted January 14, 2020 As said above, you'll need a cable capable of 70A just to drive the solenoid of the starter. That seems a bit absurd to me if the solenoid only requires 13A to hold. Also see recent comments about finding lugs small enough to even fit on the PMGR. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 14, 2020 Author Share Posted January 14, 2020 Also see recent comments about finding lugs small enough to even fit on the PMGR. I think we may be typing at cross-purposes. I'll use the 70a-capable relay just like you are using the 40a-capable one. No need for a great big cable from it. What did the factory use? 10 gauge? For documentation purposes, here's what I found, with the box being laid out this way. But note that Relay #2 only has small wires to/from its 30/70 terminals. That will have to be changed to use it for any of the uses I have planned. _____________ | | | #2 #1 | | | | #3 Big | ------------------ Big Relay: 30 = R/Bk - large 87 = R/LB - large 85 = Gn/Bk 86 = R/Bk - small (Note: There are two small R/Bk wires) #1 Relay: 30 = Y/Bk - large 87 = Blue - large 85 = R/Pk 86 = R/Bk - small (Note: there are two small R/Bk wires) #2 Relay: 30 = Y/DG - small (Note: this goes to 86 also) 87 = Y/LG - small 85 = DB - small 86 = Y/DG - small (Note: this goes to 30 also) #3 Relay: 30 = Bk/LG - large 87 = Y/LB - large 85 = Bk - small 86 = WPk - small | Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted January 14, 2020 Share Posted January 14, 2020 I think we may be typing at cross-purposes. I'll use the 70a-capable relay just like you are using the 40a-capable one. No need for a great big cable from it. What did the factory use? 10 gauge? For documentation purposes, here's what I found, with the box being laid out this way. But note that Relay #2 only has small wires to/from its 30/70 terminals. That will have to be changed to use it for any of the uses I have planned. _____________ | | | #2 #1 | | | | #3 Big | ------------------ Big Relay: 30 = R/Bk - large 87 = R/LB - large 85 = Gn/Bk 86 = R/Bk - small (Note: There are two small R/Bk wires) #1 Relay: 30 = Y/Bk - large 87 = Blue - large 85 = R/Pk 86 = R/Bk - small (Note: there are two small R/Bk wires) #2 Relay: 30 = Y/DG - small (Note: this goes to 86 also) 87 = Y/LG - small 85 = DB - small 86 = Y/DG - small (Note: this goes to 30 also) #3 Relay: 30 = Bk/LG - large 87 = Y/LB - large 85 = Bk - small 86 = WPk - small | I think it might have been 12. I guess it depends on what you choose to feed that relay. I have a 6Ga. Bus coming right off the Megafuse, so I'd need to put it through a 40A fuse on the output. I'm assuming #70 is a Ford convention? And this = 87 on a Bosch? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted January 14, 2020 Share Posted January 14, 2020 I think we may be typing at cross-purposes. I'll use the 70a-capable relay just like you are using the 40a-capable one. No need for a great big cable from it. What did the factory use? 10 gauge? For documentation purposes, here's what I found, with the box being laid out this way. But note that Relay #2 only has small wires to/from its 30/70 terminals. That will have to be changed to use it for any of the uses I have planned. _____________ | | | #2 #1 | | | | #3 Big | ------------------ Big Relay: 30 = R/Bk - large 87 = R/LB - large 85 = Gn/Bk 86 = R/Bk - small (Note: There are two small R/Bk wires) #1 Relay: 30 = Y/Bk - large 87 = Blue - large 85 = R/Pk 86 = R/Bk - small (Note: there are two small R/Bk wires) #2 Relay: 30 = Y/DG - small (Note: this goes to 86 also) 87 = Y/LG - small 85 = DB - small 86 = Y/DG - small (Note: this goes to 30 also) #3 Relay: 30 = Bk/LG - large 87 = Y/LB - large 85 = Bk - small 86 = WPk - small | What's the point of#2? Doesn't make sense to me. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 14, 2020 Author Share Posted January 14, 2020 What's the point of#2? Doesn't make sense to me. My bad! I fixed it. Should have been 87, not 70. And you have a good point about fuses! I need one for the two headlight relays, one for the starter relay, and one for the heater relay. Sure would be nice to find a box with room for those relays and fuses. I think I'll keep looking. But, I have no idea what the purpose is for #2. It had to have been just to provide a signal. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted January 14, 2020 Share Posted January 14, 2020 I have no idea what the purpose is for #2. It had to have been just to provide a signal. But if you're using the same wire to trigger and power the relay, what is it's purpose? Convention has 85 trigger and 86 ground. So 85 pulls 87 low? Link to comment Share on other sites More sharing options...
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