Parsnip

Hey renix buddy's,
So my 90 died a few weeks back, turned out to be the b+ latch relay was not tripping and giving me fuel or spark. I've given it a temp fix by jumping the terminals so it runs, but every morning when I go to start her the battery is dead. What could cause this issue? Its not the relays I've tested it with 3 other known good relays and none of them work on that slot. Is the relay panel they sit in shot? Is there a way to test it replace it? Any help is appreciated

hankthetank

the latch relay is energized during key on. when off the ecu gives it power for three-five seconds to reset the position of the idle stepper. so with your dmm, check terminal one for battery voltage, 2 is ground to ecu, 4 is to the diag conector, and 5 is b+ to ecu.

which terminals did you jump?

Parsnip

It would be the 35-86 ( I think ) , the slots that give power allowing the fuel pump to prime and spark

hankthetank

30 would be battery voltage from fusible link, 86 would be for the latch relay ground...

so you might have jumped battery to ground.

you should meter stuff before you start shorting terminals.

Parsnip

It was the part of the relay that goes from power to accessory

hankthetank

pretty sure we are not talking about the same thing...the latch relay only powers the idle stepper motor via the ecu...

sorry i can't help

DFlintstone

Agreed, the IAC needs power for a few seconds after you turn off to be ready to start. I don't know what else the latch relay might do.

DFlintstone

Hey...there is a diagram out there that shows the relays in the wrong place. Check the diagram in my signature....the fuel pump relay might be what you want to see.

mordway

Found this thread because I am having some Battery + relay weirdness. Mine (1990 Renix system) seems to energize properly, but won't unlatch.

I'm away from the vehicle, but looking at a general 5 pin relay pinout diagram and am now wondering if it is wired incorrectly. Looking straight down at the relay from top - the 6 o'clock pin, 30, is the connection to the fusible link. The 9 o'clock pin, 85?, has black wires or one black wire and I believe would find its/their way to the ECU ground for the latch system. The 12 o'clock pin, 87, is a pink wire and is energized when the key is on as is the 3 o'clock pin, 86. what I noticed is that the 3 o'clock pin stays energized after the key is turned off but that does not make sense whether or not things are wired correctly. I have not checked to see if the 12 o'clock pin also stays energized - it should really be the switched pin, correct? It looks like the 12 and 3 o'clock pins eventually are connected so I assume both are energized when the key is on.

How does the ECU then unlatch the circuit? is there a timer built in the disconnects ground? Could the issue be within the ECU?

Do either of you guys have a part number for the proper relay in the latch system or is a standard automotive 5 pin relay fine?

I am getting a "Battery + open" code on my reader. and of course the circuit is remaining energized and I would think running the battery down.

If the fault is within the ECU - do you see any issue using a timed latching relay to do the same thing but external to the ECU? I'm thinking of the Beuler BU509TD

Many thanks for all the work you guys do on these forums!!
-Mark