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Wiring a 08 GMC 2500 with my 02 harness?

Discussion in 'Fisher Engineering Discussion' started by Subseven, Feb 2, 2011.

  1. Subseven

    Subseven Member
    Messages: 44

    Can I use my wiring harness from my 2002 GMC 2500 to wire up my MM2 Fisher Easy-V to my 2008 GMC2500 HD?

    If so, what adapter or extra part would I need? Also, if you have that part...and might be willing part with it, how much?
     
  2. chevyzrule810

    chevyzrule810 PlowSite.com Addict
    Messages: 1,239

    you would have to look at the e-match system on the fisher website and see if your isolation module numbers match up to the 2008.I do know that the pushplates will fit.
     
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Do not use the old two plug relay system on an 07-newer GM, they don't coincide well at all. In other words it's time to update to an Iso system. Expensive?...yes. The correct way and much safer for the truck? Absolutely.
     
  4. chevyzrule810

    chevyzrule810 PlowSite.com Addict
    Messages: 1,239

    my friend has 2001 chevy with a 3 port isolation module 3 plug system
     
  5. Subseven

    Subseven Member
    Messages: 44

    First of all...THANKS.

    Yeah. They are saying it's $500 installed for the new setup.

    It is looking like the 3 Port Isolation Module is the same number 29070-1
    It is showing that the Headlamp Harness is different. The 2008 uses number 29400-2 and the 2002 uses a number 29048.

    So basically it's a $200 part (Headlight Harness #29400-2) I need to make it work.

    Next question...is the whole wiring setup hard to wire and hook up my self? I am not afraid to dive into it.
     
    Last edited: Feb 3, 2011
  6. Subseven

    Subseven Member
    Messages: 44

    The old one was a 4 port...so we have to convert
     
  7. Subseven

    Subseven Member
    Messages: 44

    So the Fisher dealer told us all we needed was a 3 Port Isolation Module and a new light harness to go with our old main harness from the 4 Port system that was on the 2002. Part numbers 29400-2 and 29070. It also came with a couple adapters so we could tie the old main harness into the new light harness. Cost us $375.

    Now we are trying to put this setup on the 2008 GMC 2500 HD.

    1. I plugged everything to the new 3 port module and hooked up the plugs to the headlights. I assume we have to do some splicing with the few wires (they're marked) near the headlights. Can anybody elaborate on how to do this? Especially if you already know the wires to splice to or can look at your 2008. Otherwise...I assume I'll have to use a test light and try to figure it out as the little wires near the headlight plugs are indeed marked.

    2. The connection to the battery. On his old setup from his 2002 2500, he has a different solenoid than what is shows in the diagram. They said that would be fine.

    We have no power to the plow lights or the plow.
     
  8. BTRBLDR

    BTRBLDR Member
    Messages: 38

    I took my push plates and 4 port iso module from my 06 2500 and installed it on my 08 2500. Only change I needed was a new headlamp harness.......
     
  9. Subseven

    Subseven Member
    Messages: 44

    Can you elaborate on this? Are you talking where the power wire and ground hook on that block on the firewall on the passenger side of the 2008?
     
  10. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    No I was referring to the fact that if your original system was the old two plug relay system (non Iso), do not attempt to use it on an 07-up truck.
     
  11. Me too...

    I've used the same 4 port iso 3 plug system in 3 different GMCs from '99 to my present '04. The only thing I had to change (until I got my EZV) was the headlamp harness.
     
  12. chevyzrule810

    chevyzrule810 PlowSite.com Addict
    Messages: 1,239

    I just reread your post.Yeah you need an isolation module, didn't realize your old setup was a two plug system
     
  13. Subseven

    Subseven Member
    Messages: 44

    We have the new 3 Port Module. The new light harness too. And the adapter.

    We got the plow working...but something is making the mode light on the controller keep coming on intermittently or even blinking.

    Any ideas?
     
  14. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Poor or incorrect connection on the red 12v ignition source is the common one. Where exactly is it now?

    I see faulty inline fuse holders occasionally as well.
     
  15. MOXIE

    MOXIE Member
    Messages: 38

    07 to 08 changes

    The big change is that on 07 GM trucks, when you switch to high beam, the low beams go out. On 08 and up, the lows stay on when you switch to high beams. Fisher did not want both high and low on together, so they came up with an adapter harness that shuts off the lows when switching to high beams.
    MOXIE