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Dan
Dan, Technician
Category: Saturn
Satisfied Customers: 23591
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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My 2000 saturn ls fuel pump relay want lock in. Why?

Customer Question

My 2000 saturn ls fuel pump relay want lock in. Why?
Submitted: 4 years ago.
Category: Saturn
Expert:  Dan replied 4 years ago.

Have you tried to bypass the fuel pump relay to see if vehicle runs? does it click at all? Thanks.

Customer: replied 4 years ago.

fuel pump runs if you by pass relay.Relay prong 87 has power on it. 85 has power when key is on. 86 has about 15 ohms resistance. I don't know if the engine will run when I bypass the relay. I have the tank off.

Expert:  Dan replied 4 years ago.
Did you do a fuel pressure test before removing? The fuel pump relay will only engergize fora couple seconds then shut off if vehicle isnt running...What was fuel pressure? Did you check for spark? Thanks.
Customer: replied 4 years ago.
fuel pump relay has been changed,checked,It will not engage the fuel pump, There is no power to the pump. I have checked the wiring to pump from relay base. relay has been checked and is working properly,also it has been changed. The relay will not lock in. You say the pump will only run for a few seconds when first turned on, That is what I have read,that is also the reason I have the pump disconnected from the engine. Something is keeping the relay from latching.
Expert:  Dan replied 4 years ago.
Have you checked the relay itself to see if it clicks when key is first turned on? Thanks.
Customer: replied 4 years ago.

The relay will not lock in. I have removed the relay and checked it with a meter and it locks in when power is applied. I have exchanged the relay with one exactly like it. I have turned the key on with the relay in place and listened with a stethascope. No click,and no power to pump.

Expert:  Dan replied 4 years ago.
At relay two terminals should have power and one should have ground, let me know. Thanks.
Customer: replied 4 years ago.
with the relay removed,the base pin 87 has power on it. The base pin 85 has power when the key is on. The base pin 30 is ground. The base pin 86 has a 12 to 15 ohms resistance.
Expert:  Dan replied 4 years ago.

both orangef wires going to relay should have voltage and light green should have ground while trying to start...If all are working then relay should be activating..>If this is the case check to see if gray wire leaving relay has voltage while trying to start if so but grey wire at pump does not have votlage run a new wire. let me know if you have questions, thanks.

Customer: replied 4 years ago.
I have checked voltage on grey wire and have voltage when I jump past the relay. There is voltage on both terminals and relay will not lock in.
Expert:  Dan replied 4 years ago.
does light green wire have ground? This is control circuit for relay that computer grounds to activate.
Customer: replied 4 years ago.
I don't know what color the wire is,because it is in the molded base. The control circuit number 86 terminal has a 32 ohm resistance.
Expert:  Dan replied 4 years ago.
At relay check to see 2 terminals have power and 1 terminal should have ground while trying to start...Your missing one of the 3 if relay doesnt even click when turning key from off to on.
Customer: replied 4 years ago.
back to your recent answer,the control circuit is only partly grounded,it has a 32ohm resistance.
Expert:  Dan replied 4 years ago.
Then check wire between relay and pcm to see if wire is good...If not replace wire...if good see if pcm connection is good...If so see if pcm is grounding wire...If not check pcm grounds to verify good and if so replace pcm.
Customer: replied 4 years ago.

Dan, I think we are onto something now. I pulled the wires off of the pcm and the resistance went to zero. I checked the wire to the plug from relay and found it to be perfect. i am assuming that the pcm is faulty and is not controling the fuel pump relay. Do you agree?

Expert:  Dan replied 4 years ago.
Check resistance on wire between alternator and pcm...resistance of wire should be under 5 ohms...if resistance is good, connector is good, and pcm has good power/ground then replace pcm.
Dan and 4 other Saturn Specialists are ready to help you
Customer: replied 4 years ago.
Sorry for not getting back to you. I sent the ecm off to be tested and was told,that they couldn't repair it. I have a used one coming. When it gets here,I will install and let you know something,Thanks,Raymond
Expert:  Dan replied 4 years ago.
Sounds good, let me know how it goes. thanks.