3 Relays

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?

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.

owners manual... Your kidding me right?

owners manual... Your kidding me right?

:hmm:

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..

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.

Rear = Oxygen Sensor Heater Relay

Middle = Fuel Pump Relay

Front = Power Latch Relay

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?

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

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.

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:

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:

thanks. i get it. :bowdown:

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.