FamilySHO
SHO Member
The fuel pump on my 1992 SHO stopped working a couple of days ago. The only good thing is that it happened in my driveway and not in the middle of nowhere with the wife and kids. I did a search for a fuel pump diagnostic and found an excellent one by project89sho: http://www.shoforum.com/showthread.php?t=9116. The Service Manual has a similar diagnostic in its "Fuel Systems-Service" section. Part of the testing is done on the ICRM above the radiator. Despite the fact that there are a number of threads further elaborating on the diagnostic, being severely mechanically/electronically challenged, I have a few questions. For clarity I'm going to repeat project89sho's diagnostic and then ask my (dumb) questions).
"1. Ground the FP test point on the EEC-IV connector. See the EEC self-test section of the FAQs at http://www.shotimes.com/SHO3eeccodes.html All voltage readings are referenced to a good chassis ground, unless otherwise specified. This activates the IDLE FP Relay.
2. Fuel pump SHOULD be running. If not, go to Step 3.
3. Measure at pin 5 of the ICM (PK/BK)to ground. You should measure partial battery voltage (I'll measure mine tomorrow). If so, go to step 6.
If reading is full battery voltage, there is an open circuit in the load side - Inertia switch, or FP. Go to step 4.
If reading is 0 volts, GO TO STEP 5.
4. Check inertia switch, reset as needed. Measure voltage on both leads. A good switch will have the same voltage on both leads as measured in step 3 above. If not, jumper across the switch and see if the FP runs. If so, replace the switch. Measure the voltage at the FP terminals. If you measure the same voltage at the input and the ground is good (verify it), replace the FP. If the voltage is lost at some point, you have an open circuit between that point and the previous point that did have voltage.
5. Measure ICM pin 10. If reading is full battery voltage, the FP relay in the ICM is bad. Replace or repair ICM. If reading is 0 volts, check the voltages on both leads of dropping resistor. If the readings are both 0 volts, there is an open circuit between the reistor and Fuse Link J. If one lead of
the resistor measures 0 volts and the other side reads battery voltage, the resistor is open. You can temporarily jump the resistor to see if the pump will run.
6. The FP should be running at "idle" speed. Listen carefully or have an assistant help."
All right now my questions.
1. Are all tests done on the IRCM with the FP test point still grounded?
2. The IRCM connector, the male end, has slots for 24 pins, 12 on the top and 12 on the bottom, but six are empty for 18 total pins. In determining the number of a pin, for example pin 5, would all the slots be counted whether there's a pin inserted or not?
3. In looking at the male end the pins would be counted right to left to determine the pin number, correct?
4. Both the service manual and threads elaborating on the diagnostic seem to indicate that the connector must be plugged into the IRCM in order to test voltage at the pins. This would require the individual pin to be pulled out of the connector for testing. Is this right? If so would it be all right to pull the wire out of the connector with say needle nose pliers? I don't want to do something which would damage the connector or the wiring, which is why I ask.
Unfortunately I may have more questions depending on hwo the IRCM tests. Please bear with me and thanks for the help.
"1. Ground the FP test point on the EEC-IV connector. See the EEC self-test section of the FAQs at http://www.shotimes.com/SHO3eeccodes.html All voltage readings are referenced to a good chassis ground, unless otherwise specified. This activates the IDLE FP Relay.
2. Fuel pump SHOULD be running. If not, go to Step 3.
3. Measure at pin 5 of the ICM (PK/BK)to ground. You should measure partial battery voltage (I'll measure mine tomorrow). If so, go to step 6.
If reading is full battery voltage, there is an open circuit in the load side - Inertia switch, or FP. Go to step 4.
If reading is 0 volts, GO TO STEP 5.
4. Check inertia switch, reset as needed. Measure voltage on both leads. A good switch will have the same voltage on both leads as measured in step 3 above. If not, jumper across the switch and see if the FP runs. If so, replace the switch. Measure the voltage at the FP terminals. If you measure the same voltage at the input and the ground is good (verify it), replace the FP. If the voltage is lost at some point, you have an open circuit between that point and the previous point that did have voltage.
5. Measure ICM pin 10. If reading is full battery voltage, the FP relay in the ICM is bad. Replace or repair ICM. If reading is 0 volts, check the voltages on both leads of dropping resistor. If the readings are both 0 volts, there is an open circuit between the reistor and Fuse Link J. If one lead of
the resistor measures 0 volts and the other side reads battery voltage, the resistor is open. You can temporarily jump the resistor to see if the pump will run.
6. The FP should be running at "idle" speed. Listen carefully or have an assistant help."
All right now my questions.
1. Are all tests done on the IRCM with the FP test point still grounded?
2. The IRCM connector, the male end, has slots for 24 pins, 12 on the top and 12 on the bottom, but six are empty for 18 total pins. In determining the number of a pin, for example pin 5, would all the slots be counted whether there's a pin inserted or not?
3. In looking at the male end the pins would be counted right to left to determine the pin number, correct?
4. Both the service manual and threads elaborating on the diagnostic seem to indicate that the connector must be plugged into the IRCM in order to test voltage at the pins. This would require the individual pin to be pulled out of the connector for testing. Is this right? If so would it be all right to pull the wire out of the connector with say needle nose pliers? I don't want to do something which would damage the connector or the wiring, which is why I ask.
Unfortunately I may have more questions depending on hwo the IRCM tests. Please bear with me and thanks for the help.
