relay latching problem

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bigblockranger

Member - Posts: 8

Joined: July 21, 2009

Location: Texas, United States

Posted: July 21, 2009 at 8:35 AM / IP Logged

I am setting up a cooling fan relay and a relay to activate my electric crankcase evac pump triggered by my ECM, (-) trigger.

Once these come on, they are on until you disconnect the battery.

I currently have it wired like this:

but believe it *should* be like this:

Will having the 30 & 87 flip flopped cause this latching condition?

'86 Ford Ranger 545/C6/EFI

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howie ll

Pot Metal - Posts: 16,466

Joined: January 09, 2007

Location: United Kingdom

Posted: July 21, 2009 at 11:46 AM / IP Logged

Either way makes no difference, try a diode across 86 and 85 with the band towards 86.

bigblockranger

Member - Posts: 8

Joined: July 21, 2009

Location: Texas, United States

Posted: July 21, 2009 at 3:07 PM / IP Logged

I do have a diode (correctly oriented) and once you ground the coil, they are on all the time until you disconnect the battery. You can even disconnect the coil ground and it makes no difference.

Both of these circuits worked fine with a toggle wired with a switched (+). I may just configure it to work that way with the ECM since I know it worked well that way. Just did not want to have to rewire all that stuff again.

'86 Ford Ranger 545/C6/EFI

i am an idiot

Platinum - Posts: 13,674

This member consistently provides reliable information

Joined: September 21, 2006

Location: Louisiana, United States

Posted: July 21, 2009 at 5:40 PM / IP Logged

The lower picture will not latch. It will only be on as long as the - trigger wire is at ground. Do you need it to latch until you turn the key off?

Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB

bigblockranger

Member - Posts: 8

Joined: July 21, 2009

Location: Texas, United States

Posted: July 21, 2009 at 5:49 PM / IP Logged

No. Both are set up like the bottom pic and they definitely are latching. I do not want them to.

I have the ability to change from a (-) switching to a (+) so i will just do it that way and be done.

'86 Ford Ranger 545/C6/EFI

i am an idiot

Platinum - Posts: 13,674

Joined: September 21, 2006

Location: Louisiana, United States

Posted: July 21, 2009 at 6:22 PM / IP Logged

The bottom pic will not latch. If it is staying on, it is because the - signal is remaining on terminal 85. Upon further review, neither of them will latch. When it latches, remove the trigger wire from 85 and see if it turns off. If that is the case, your trigger wire is still at ground.

How do you want the relay to react? Do you want it to come on and remain on until you turn the key off?

Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB

howie ll

Pot Metal - Posts: 16,466

Joined: January 09, 2007

Location: United Kingdom

Posted: July 22, 2009 at 3:05 AM / IP Logged

Meter 30 and 87 with nothing connected in case you have a sticky relay, is that possible. Otherwise I'm with Mr.Idiot on the 85 lead. Test it , also make sure the diode band faces 86 (pos side of coil), further reading makes think it's not a relay problem because from what you're saying you have two relays doing the same thing.

bigblockranger

Member - Posts: 8

Joined: July 21, 2009

Location: Texas, United States

Posted: July 22, 2009 at 1:23 PM / IP Logged

Thanks for the input. In my haste I jumped to the conclusion that the relay must be the problem, but now think it lies in my transistor circuit that grounds the relay.

-James

'86 Ford Ranger 545/C6/EFI

hotwaterwizard

Silver - Posts: 1,350

Joined: December 11, 2003

Location: California, United States

Posted: July 23, 2009 at 8:20 AM / IP Logged

I Have seen this before.

The load keeps the contact from unlatching when the relay has a weak return spring.

A different style relay will usually fix the problem.

Try a Ford Starter Relay for $10

John DeRosa (Hotwaterwizard)

Stockton California

When in doubt, try it out !

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bigblockranger

Member - Posts: 8

Joined: July 21, 2009

Location: Texas, United States

Posted: July 23, 2009 at 8:33 AM / IP Logged

Thanks.

I rebuilt the switching circuits last night using TIP120's instead of the smaller 2N2222A's and it now works perfect. I ran across another fellow that was having the same problem. Surprisingly, we independently came up with the same solution. haha

Thanks for the help.

'86 Ford Ranger 545/C6/EFI

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