1992 Isuzu rodeo 3.1 no spark I have change almost everything that I can think of except for my ecm relay could this be at fault ?
1992 no spark on all 6 cylinders.ok, did you first look at the schematic on ECU and SparK>?lets do that and see. now.spark systems are vastly changed, from 1990 to 2000evolutionary, that means I must look up what's there first.lets tick them off.1: fuses good, means test them if they L**k good.there are 6 fuse here , for this to work. 2 for ECU relay.2: head lamps work (bright, ok battery seems strong) and cranks.3:key on , cluster glows, and all those warning lamps, but but the CEL it must glow, or the ECU has no power, the ecu fires the coil via an Ignitor so ECU must have power and CEL glowsCheck engine light.if that work the engage the diag jumper wire clipthis enables flash diagnostic codes. then crank for 5seconds, if you get the code for dead CKP bingo.how do to that is here.http://www.troublecodes.net/isuzu/now your relay question?key on, all wires on the relay go hot 12vdc.but the black wire (its ground)the 2 green wires on relay must be 12vdc, output to ecu. the inputs are fused x2to test a so called good looking fuse.we use 2 methods, ill show 1.ohms. with your DMM set to Rx1 range (lowest)measure he fuse. 0 ohms good, infinity bad.we use volts on key on car, 12vdc both sides of fuse.there are some rare exception on that, (fused grounds)but not this car.the fuse related are hot all time, or hot keyon.