Author Topic: ECM 1 fuse blowing 1987 chevy  (Read 2660 times)

Offline Yellowcat

  • Newbie
  • Posts: 16
  • Newbie
Re: ECM 1 fuse blowing 1987 chevy
« Reply #15 on: September 02, 2025, 06:13:23 pm »
I touched the probes on all different pins of the ESC  just to see if anything would happen...... it every time it just stays on the letters OL. I done all these three separate tests with the ignition key switch off

Offline Yellowcat

  • Newbie
  • Posts: 16
  • Newbie
Re: ECM 1 fuse blowing 1987 chevy
« Reply #16 on: September 02, 2025, 06:38:25 pm »
Also as I have stated before the wires going to the fuel relay do not have power when turning the ignition key on the only wire that has constant power when the key is off is the orange wire

Online bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6608
Re: ECM 1 fuse blowing 1987 chevy
« Reply #17 on: September 02, 2025, 06:41:21 pm »
Don't be alarmed by the 'OL' measurement on your meter.  OL means overload, indicating the circuit is effectively open from the perspective of the ohmmeter.  The ESC module, unlike the EGR solenoid and EAC valve solenoid, contains an integrated circuit with very high internal impedance that conducts microamps of current.  The EGR and EAC solenoids are electromagnets with moderately low impedance flowing approximately 1 amp each.  That's 6 orders of magnitude difference.  The primary concern was to discover whether the ESC module is shorted.  It is not. 

Simply for the sake of interest, recheck the ESC pins reversing the probe polarities to see if there is any difference and let us know. 

Regarding the fuel pump, will the engine start and run?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Online bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6608
Re: ECM 1 fuse blowing 1987 chevy
« Reply #18 on: September 02, 2025, 06:43:20 pm »
You didn't say if the EGR and EAC solenoids measured greater than 10 ohms...?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Online bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6608
Re: ECM 1 fuse blowing 1987 chevy
« Reply #19 on: September 02, 2025, 06:45:33 pm »
What does the meter indicate if you touch the two ohmmeter probes together?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Yellowcat

  • Newbie
  • Posts: 16
  • Newbie
Re: ECM 1 fuse blowing 1987 chevy
« Reply #20 on: September 02, 2025, 09:03:04 pm »
The multimeter buzzes and goes to 0 when the probes are touched.. the EGR and EAC tested both at 37ohms. The truck will not start and run because I can't get power to fuel relay like it's suppose to have or power to the pump when I tried to  jump it from the pigtail on the fuel relay. Why is there no power to the green and white wire on e fuel pump relay when you turn ignition on??

Online bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6608
Re: ECM 1 fuse blowing 1987 chevy
« Reply #21 on: Today at 02:00:04 am »
See below.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)