Outer Limits 4x4 Board

I am going through the wiring for a SQ416 Grand Vitara, as I have an engine out of one for a transplant into my Sierra.

So far identifying wiring etc has been quite simple.
One thing has me completely lost however. There is a item wired to the ECM in the diagram listed as "pump", however the "fuel pump" is listed elsewhere. Below are the two pages of the wiring diagram, the first showing the "fuel pump" and the 2nd showing the mystery "pump" (the red bits were added by me).

I first thought it was a secondary fuel pump, however have not found any evidence that the GVs run 2 fuel pumps, only a single in tank pump.

If somebody could ID what it is, and if I need it, that would be great; as the wires are in my loom, I just dont know what they are for.

stab in the dark..... would it be for the vacuum operated front hubs/diff?

so you have a plug for it? ie the end that would plug into the "PUMP" whats either side of it plug wise in the loom ? might give you some indication as to where the pump was physically situated? even if you have to go back to the car and trace what it plugged into and then what the pump does?

tanshi wrote:so you have a plug for it? ie the end that would plug into the "PUMP" whats either side of it plug wise in the loom ? might give you some indication as to where the pump was physically situated? even if you have to go back to the car and trace what it plugged into and then what the pump does?

Yes, have the plug with the three wires.
Its near to one of the headlight plugs, though on a bit of a length of wire.


Atari, I thought the vacum hubs worked off engine vacum like a brake booster?
Something to look into though.

atari4x4 wrote:stab in the dark..... would it be for the vacuum operated front hubs/diff?

With that idea, a bit of research seems to back it up
Also seems to indicate they are not vacum hubs, but possitive pressure hubs / Air hubs.

to quote a chapter heading from the SQ416/420/625 manual:

"When the 4wd switch is turned ON by shifting the transfer lever, ECM (PSM) (G16 and J20 engine models) or 4WD controller (H25 engine model) actuates (energizes) the air pump assembly. Then positive pressure is sent from the air pump assembly to the actuator installed to the differential case and causes the axle lock clutch and the free axle hub in the differential case to be engaged, resulting in the 4WD mode. Only when running in the 4WD mode, front axles are joined to differential case, and they become free when 2WD mode is used (or when transfer shift is shifted to N position), thereby reducing the power loss."

Thanks.

sweet, i'm glad my stab in the dark actually brought some tech!!