Testing Combi-relay Outputs
 

Any of you guys have experience with '74 1.8 F.I. system dual relay? I'm having a tough time trying to test the little black box that sends voltage to the following components:
Air flow meter terminals 86b and88a
F.I. resistors terminal 88b
Aux. air valve terminal 88c
Cold start valve terminal 86
Coil terminal 86c
Fuel pump terminal 88d
Sure would like to know the voltages at these terminals with the ignition on. Thanks in advance for your help. Al

the voltages are all 12 volt or ground,

the power comes from the coil to turn on the relay which sends power to the fi brain it also send power to the fuel pump switch in the air flow meter

the big red wires are the power to the fuel pump

ignore the white wires they go to the fuel injectors and the brain

the coil gets it power from the reg board

if you need mor einfo email me and we can talk i have just about rebuilt mine

First check for battery voltage (12V+) at 88z (power from battery) then voltage at 86c (power from coil terminal 15) with the key on and make sure that terminal 85 goes to a good ground.

88a - power out to air flow meter contact - 12V with the key on

86b - power in from air flow meter contact - 12V when cranking (with no big vacuum leaks) or moving the airflow flap by hand

88d - power out to the fuel pump - 12V when cranking or moving the airflow flap by hand

88c - power out to the aux air regulator - 12V when cranking or moving the airflow flap by hand

88b - power out to ECU and resistor pack - 12V with key on

86a - power in from starter terminal 50 - 12V when cranking

86 - power out from 86a to cold start valve and ECU - 12V when cranking

Scott & EJ: Thanks for the quick response, your information is just what I need. I was getting 12v. on 88a & 88z but 0v. on 88c, duh, need to crank! O.K. Tomorrow I'll check all the other terminals per your instructions. I have been having unexplained shutdowns with a usually good running engine, thought it may be a broken wire or bad terminal so as I moved the plugs on the relay I noticed it was real hot 140 degrees, that led to checking it out. Maybe tomorrow will tell. Thanks again, Al