testing relays

[Tim P.]

does anyone have any knowledge on testing relays howto kinda thing or a place of reference that will help me understand theses darn things I think I have a bad relay

Thanks Guys

Tim P.

[ToughOldFord]

Assuming you mean starter relay:

http://www.fordification.com/forum/view ... 796#123796

[Wes]

relay's are very simple electro magnet devices, A thin wire is wrapped around a piece of steel, this the control circuit, when current is supplied to the control circuit the steel become a magnet which attracts and closes a steel contact for the load circuit. This a normally open relay. (open at rest ) this the type our truck use for a starter solenoid.

A normally closed has the same circuits, but powers the controls circuit to open the load circuit.

are you still have starter run on problems Tim ??
If so I starting to think your starter may be drawing way to may amps, welding the solenoid closed.
Before starting this testing please remove starter side cable from solenoid.
To test is easy have battery power to 1 side of load circuit , (Large stud closest to battery) both small wire removed, check for voltage on opposite stud,( large stud starter side) if voltage it's welded closed and is no good.
If no voltage, apply battery power to small "S" terminal (control circuit ). Check for voltage at starter stud. Is there voltage ? Yes remove power from from "S" terminal, recheck voltage at starter stud should read 0, if not solenoid is bad.
I hope this helps clear it up. take 1 apart and look at it.

[Tim P.]

nope fixed that problem but It was running several times but it will stop runnung suddently and wont start again until it feels like it I want to test the relays for fuel and the EEC relay I have replaced the control module and the magnato inside the dizzy the coil cap rotor wires plugs and solanoid switch so basicy that leaves the eec or fuel relay perhaps,,, need help getting tired of this truck issues ( I really like my old bumpside)

[Wes]

It's the same normally open relay only smaller, can test same way just have to figure out witch terminal does what.
The original fuel pump relay was green, eec power relay white, a/c control relay gray, the updated service part from Ford is black and can be used for all 3 relays.
The fuel pump relay gets hammered the most, esp when pump is getting older and drawing more amps.
Refresh my memory your working on the 96 or the 72 ?

[Tim P.]

90 ranger 2.9l v6 it has a green relay a white and gray most likely original 164k on motor and chassis

[Tim P.]

Took it truck to the ford dealer as Im at the point that what ever the problem is is in the computer and Im not setup for that type of testing all other test were checked good

[Jake11]

Wanna know how the "wizards" at the dealership test them? I'll tell
you. They plug a new one in and see if it works. If that don't work,
they cry "uncle". Then tell you trade it in.

[Tim P.]

Aint that the truth+ they get $65 an hour for there tech knowledge