Starter relay wiring

15

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.

15

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.

15

The PCM ended up being bad.

Your Answer:

F-150

Looking for a Used F-150 in your area?

CarGurus has 11,522 nationwide F-150 listings starting at $3,900.

Postal Code:

Ford F-150 Experts

  • #1
    OJ
    Reputation
    11,220
  • #2
    dandyoun
    Reputation
    5,020
  • #3
    tennisshoes
    Reputation
    3,950
View All

Related Models For Sale

Used Chevrolet Silverado 1500
99 Great Deals out of 11,091 listings starting at $4,950
Used GMC Sierra 1500
82 Great Deals out of 10,268 listings starting at $5,795
Used Ford F-250 Super Duty
20 Great Deals out of 829 listings starting at $3,995
Used Toyota Tundra
29 Great Deals out of 1,495 listings starting at $4,500
Used Dodge Ram 1500
33 Great Deals out of 520 listings starting at $2,500
Used Toyota Tacoma
17 Great Deals out of 1,738 listings starting at $6,413
Used Ford Mustang
36 Great Deals out of 1,236 listings starting at $3,995
Used Ford F-350 Super Duty
19 Great Deals out of 1,213 listings starting at $6,999
Used Chevrolet Colorado
10 Great Deals out of 2,327 listings starting at $3,995
Used Nissan Titan
31 Great Deals out of 888 listings starting at $4,960
Used Chevrolet Silverado 2500HD
11 Great Deals out of 1,175 listings starting at $4,495
Used Ford Explorer
20 Great Deals out of 1,734 listings starting at $2,500
Used Chevrolet Tahoe
10 Great Deals out of 792 listings starting at $5,900

Used Cars For Sale

2018 Ford F-150 Lariat SuperCrew 4WD For Sale
1,483 listings starting at $45,035
2017 Ford F-150 Lariat SuperCrew 4WD For Sale
100 listings starting at $37,985
2016 Ford F-150 Lariat SuperCrew 4WD For Sale
72 listings starting at $32,899
2015 Ford F-150 Lariat SuperCrew 4WD For Sale
4 Great Deals out of 60 listings starting at $29,900
2014 Ford F-150 Lariat SuperCrew 4WD For Sale
19 listings starting at $29,750

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.