Starter relay wiring

5

Asked by Jan 24, 2017 at 11:17 PM about the 2008 Ford F-150 Lariat SuperCrew 4WD

Question type: Maintenance & Repair

My 2008 Ford F150 has been having intermittent starting issues. It has been a rather frustrating process to deal with. I first replaced the battery, then I replaced the starter because I was told it was the problem (tested at Autozone) and finally I replaced the neutral safety switch. I tried switching my starter solenoid relay (R01) with my Hi beam headlamps (R03) relay and there was a half crank but it didn't fix it. When I switched it back I also got a half crank. I pushed and moved the relay around as I turned the key and it started to crank. I let my hand off the key and it continued to crank and started. I tried this again today but wasn't able to get it started at first. Eventually I got the truck started and I think there's not a good contact between the relay and wire going to starter or that wire is bad. I've tried looking into what the wire from the starter ignition point to relay box is called or if it's a specific part but I can't find much. I know from the repair manual that it's yellow/blue wire and I confirmed that looking at the starter but beyond that us unknown. How would I go about testing this wire or replacing it? How can I obtain access behind the fuse panel? Any input is appreciated. Thanks!

4 Answers

I am having the same issue, and cannot figure out what is going on. I also think it is this wire from the solenoid to the relay box. Mine is also a 2008 F150.

5

I isolated the issue on my truck. I tested my started relay (R01) connections. I removed R01 and looked for 12V on pin 30 (constant hot) then I looked for 12V on pin 86 (cranking). These two points of contact have 12V so I knew I was getting power. I then tested the grounds and terminal 87 has a good ground but my terminal 85 does not have a good ground. The PCM (computer) is what allows the signal to ground when certain criteria are met. This is the point where I'm stuck because the only information I could find on this was... the neutral safety switch, crankcase and crankshaft position sensors, or wiring. I've already replaced the neutral safety switch and I don't think it's the crankcase or crankshaft position sensors because the truck runs fine and doesn't throw any codes. Temp Fix- My temporary fix for now is to ground terminal 85 myself. This overrides the computer and allows my truck to start. I wrapped some wire around terminal 85 and grounded it to some metal by my glovebox. This allows the truck to start! Let me know if you need any help walking you through something. Btw I think my problem is the PCM which is expensive so that's why I'm making this temporary fix.

Thanks Jeff. I will check the same thing. Dave in Minnesota.

5

The PCM ended up being bad.

Your Answer

F-150

Looking for a Used F-150 in your area?

CarGurus has 231,602 nationwide F-150 listings starting at $1,300.

ZIP:

Ford F-150 Experts

  • #1
    OJ
    Reputation
    9,960
  • #2
    dandyoun
    Reputation
    4,690
  • #3
    tennisshoes
    Reputation
    3,420
View All

Related Models For Sale

Used Chevrolet Silverado 1500
2,774 Great Deals out of 158,080 listings starting at $1,000
Used GMC Sierra 1500
1,161 Great Deals out of 62,193 listings starting at $1,295
Used Ford F-250 Super Duty
451 Great Deals out of 47,831 listings starting at $695
Used Toyota Tundra
660 Great Deals out of 36,619 listings starting at $1,500
Used Dodge Ram 1500
342 Great Deals out of 10,757 listings starting at $1,988
Used Toyota Tacoma
555 Great Deals out of 41,982 listings starting at $2,500
Used Ford Mustang
354 Great Deals out of 42,608 listings starting at $1,488
Used Ford F-350 Super Duty
406 Great Deals out of 27,287 listings starting at $3,900
Used Nissan Titan
328 Great Deals out of 22,029 listings starting at $1,995
Used Chevrolet Colorado
324 Great Deals out of 42,765 listings starting at $1,299
Used Chevrolet Silverado 2500HD
434 Great Deals out of 31,612 listings starting at $2,500
Used Chevrolet Tahoe
848 Great Deals out of 40,189 listings starting at $1,700
Used Ford Explorer
1,142 Great Deals out of 68,760 listings starting at $1,200

Used Cars For Sale

2018 Ford F-150 Lariat SuperCrew 4WD For Sale
10,958 listings starting at $37,999
2017 Ford F-150 Lariat SuperCrew 4WD For Sale
25 Great Deals out of 1,487 listings starting at $30,995
2016 Ford F-150 Lariat SuperCrew 4WD For Sale
20 Great Deals out of 914 listings starting at $28,000
2015 Ford F-150 Lariat SuperCrew 4WD For Sale
46 Great Deals out of 1,541 listings starting at $24,875
2014 Ford F-150 Lariat SuperCrew 4WD For Sale
49 Great Deals out of 1,061 listings starting at $14,950

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.