3 Relays

[jtdesigns]

Under the cover at the diagnostics port/connector. Which one is what relay? I was reading the wiring diagrams and came across a "B+ Latch Relay" is that pretty much the "main" ignition relay, or main power latch?

[Geonovast]

It should say in your owners manual which one's which.

 

I know the 91+ systems have it printed right under the fuse/relay block cover.

[jtdesigns]

owners manual... Your kidding me right?

[Geonovast]

owners manual... Your kidding me right?

:hmm:

[jtdesigns]

owners manual... Your kidding me right?

:hmm:

I don't have no owners manual... :rotfl2:

I guess in 20 years its turned to dust, or thrown out by some PO..

[Windowsrookie]

I've also wondered what relay does what. The relay cover does not have anything printed under it, and I also don't have an owners manual.

[Eagle]

Rear = Oxygen Sensor Heater Relay

 

Middle = Fuel Pump Relay

 

Front = Power Latch Relay

[jtdesigns]

Rear = Oxygen Sensor Heater Relay

 

Middle = Fuel Pump Relay

 

Front = Power Latch Relay

I was reading the wiring diagrams and came across a "B+ Latch Relay" is that pretty much the "main" ignition relay, or main power latch?

[dakal]

yeh what is a b+ power... relay? mean.

[Eagle]

The latch relay has something to do with shutting down the injectors when you power down. It isn't the main power center for the vehicle -- the 2.5L Renix models don't even have a latch relay.

 

That's about all I can tell you. Maybe one of the electrical/electronic genius types like Hornbrod can provide more/better info.

[jtdesigns]

yeh what is a b+ power... relay? mean.

I can only think of a latch program in a PLC. I mean ecu's are basically PLCs (programmable logic control) and theres a latch program that holds things (relays, switches, contacts, motor starters, ect) open, or closed. But the diagram doesnt go anywhere except to the ecu through a real relay.. Not like a PLC in that way cause relays are programed into the PLC PCU. :hmm:

[HOrnbrod]

The latch relay has something to do with shutting down the injectors when you power down. It isn't the main power center for the vehicle -- the 2.5L Renix models don't even have a latch relay.

 

I suspect the Renix latch relay performs the same function as the Auto Shutdown Relay (ASD) relay on the HOs. When starting the engine the ASD relay latches and looks for a + voltage signal generated when the distributor is spinning. If not, the ASD relay trips and cuts power to the + coil and the fuel pump and prevents starting. A safety thing. I had one stick on a 96 XJ I had so that's the only reason I know this. :cheers:

[dakal]

thanks. i get it. :bowdown:

[88XJSport]

I was told the B+ latch relay adjusts the IAC to a set position, in anticipation for the next restart. This is why the relay "clicks" after 3 or so seconds after the engine shuts off.

 

Again, I could have been told wrong, but thats what ive been told.