Timing and Diagnostic Check Connector location(s)
These are located on the driver's side inner fender on the earlier EFI trucks and 4Runners, later models had an integrated diagnostics box located on the passenger side of the engine bay, near the fuse box.
The small round connector at the top of the image below is the notorious "T" connector (location of the T and E1 terminals) for setting timing and checking ECU codes (circled in light blue):
On the 22RE, ignition timing is specified at 5°BTDC with the above jumper installed and the idle speed set to around 750 PRM.
The larger round connector is some other test plug (circled in green) has the ECU O2 circuit test voltages, such as the Vf signal.
There is also a small round one-wire connector (not shown in the pictures below, mine has a black rubber cap) that has the O2 sensor voltage for testing purposes.
A: Overview of early engine
Diagnostic and Test Connectors B: Early model Fuel Pump Test
Connector w/ jumper installed
C: Later model TCCS Diagnostic Connector
(orange wire plugged into it) D: Later model box w/ Fuel Pump
(FP-B+) TestJumper installed
E: TCCS Diagnostic/Timing Jumper
(E1-TE1) terminal locations F:
[Click above for a larger image]
Note: On later model trucks, there is no separate fuel pump test connector, rather you have to use the diagnostic test connector (shown in photo C above) and follow the test procedure outlined in the Factory Service Manual, which involves jumpering the "Fp" and "B+" terminals (see photo D). The Timing/Diagnostic jumper terminals (E1 - TE1) are shown in photo E.
The underlying problem is most likely that the winding on the circuit opening relay (see schematic above) that is energized by the ECU STArt signal is not working properly. Lacking this signal to energize the fuel pump, I get no fuel pressure while starting, until enough air flows through the AFM to trip its fuel pump contact. I hope to get the CO relay checked out and hopefully this will correct the problem.