Starter Relay Questions

[Ajax]

I have a couple of questions regarding the starter relay. First, with the ignition in off position, multimeter reads 12.55v across the starter relay. When the starter is engaged, the reading on the multimeter reading drops down to .90v. Is this normal operation? Can a starter relay allow the starter to crank but not allow enough juice to power the coil?

 

[Slantsixdan]

The biggest terminal on the starter relay is live all the time; that is where the main charging line (A1/A1-A on the wiring diagram) connects to the trailing lead coming from the battery end of the positive battery cable. The second-biggest terminal on the relay shoots line voltage to the starter solenoid when the key is in the "start" position. If your car has automatic transmission, there are two small terminals on the relay; one gets line voltage from the ignition switch when the key is in "Start" and the other gets grounded via the neutral safety switch. If your car has manual transmission, there is only one small terminal; it gets line voltage when the key is in "start", and the relay trigger coil is grounded via the relay housing to the body sheetmetal.

 

[beezee]

Answer to first question is yes,that,s normal because you are measuring voltage across an open contact or switch to read full voltage,your meter is measuring positive voltage to a common ground through a motor winding, coil or resister etc. When the contact closes the reading will zero as the voltage is the same on both your meter leads.
The ignition coil receives full voltage when cranking and reduces when running . The ballast resister drops voltage to protect the ignition as designed when running.

 

[Ajax]

Perfect answers, and I appreciate the responses. I am going to order a new relay from mopar performance for $42 bucks! Sheesh!

 

[Slantsixdan]

Er…why overspending for Mopar Performance's rebox of the same relay you can buy in very good quality in a Standard/BlueStreak box for seven dollars? SR-105 (automatic) or SR-106 (stick shift).