Starter relay testing/wiring

5

Asked by Jan 25, 2017 at 12:02 PM about the 2008 Ford F-150 Lariat SuperCrew 4WD

Question type: Maintenance & Repair

My 2008 Ford F150 has been having intermittent starting issues. The battery, starter and digital transmission range switch (neutral safety switch) have been replaced. I'm trying to pinpoint this issue but I've never dealt with this type of problem before. I'm learning a lot which is nice but it's frustrating not being able to locate the problem. I think the issue is either the ignition switch, starter solenoid relay (R01), or wiring. I'm leaning towards the wire coming from starter to R01 but this is all new territory for me.
I originally would rock the truck while in park and that helped me get it started most of the time. This didn't work one time and I had to let it sit for awhile and let it cool down. I recently discovered that messing with R01 seems to help get the truck started. It seems like the relay is not making a good contact or one of the wires needs to be replaced. I tried switching R01 with R03 which is my hibeam headlights but it didn't fix the problem. I got half a crank and that lead me towards the relay not making good contact or a bad wire. When I switched the relay back I got a half crank and then while cranking and jiggling the relay it started.
I've bench tested the relay out of the vehicle and it checked out. More recently I took the relay out and checked pin-out 86 for 12V while cranking and it was there. My next step is to check pin-out 86 for 12V while the vehicle won't start but I'm not sure what else to do at this point.
Any suggestions?

2 Answers

119,645

First thanks for a such a detailed question, most people write (My car won't start, HELP !, LOL) anyway you are doing everything right and there are a few things I would look at when a trouble shooting your relay, A relay is a simple device, it may work a hundred times with no issues and there will be that one time it won't. The relay itself maybe heating internally and shorting or possible a bad connection in the plug or the back where the wires attach. I would try to get a really small file and get down in there and give the connectors a good cleaning and then add some dielectric grease and see it that helps cure the issue...

5

The PCM ended up being bad.

Your Answer

Ford F-150 Experts

  • #1
    OJ
    Reputation
    10,220
  • #2
    dandyoun
    Reputation
    4,830
  • #3
    tennisshoes
    Reputation
    3,670
View All

Related Models For Sale

Used Chevrolet Silverado 1500
1,781 Great Deals out of 149,286 listings starting at $1,495
Used GMC Sierra 1500
722 Great Deals out of 58,462 listings starting at $1,900
Used Ford F-250 Super Duty
374 Great Deals out of 42,218 listings starting at $1,600
Used Toyota Tundra
478 Great Deals out of 38,526 listings starting at $1,999
Used Dodge Ram 1500
316 Great Deals out of 9,549 listings starting at $800
Used Toyota Tacoma
439 Great Deals out of 44,078 listings starting at $1,995
Used Ford Mustang
270 Great Deals out of 37,081 listings starting at $2,150
Used Chevrolet Colorado
295 Great Deals out of 41,682 listings starting at $1,900
Used Ford F-350 Super Duty
431 Great Deals out of 24,311 listings starting at $3,900
Used Nissan Titan
254 Great Deals out of 22,941 listings starting at $1,995
Used Ford Explorer
801 Great Deals out of 64,315 listings starting at $1,000
Used Chevrolet Silverado 2500HD
361 Great Deals out of 29,859 listings starting at $2,500
Used Chevrolet Tahoe
528 Great Deals out of 36,655 listings starting at $1,375

Used Cars For Sale

2018 Ford F-150 Lariat SuperCrew 4WD For Sale
14 Great Deals out of 12,056 listings starting at $34,990
2017 Ford F-150 Lariat SuperCrew 4WD For Sale
10 Great Deals out of 932 listings starting at $30,950
2016 Ford F-150 Lariat SuperCrew 4WD For Sale
10 Great Deals out of 924 listings starting at $29,499
2015 Ford F-150 Lariat SuperCrew 4WD For Sale
25 Great Deals out of 1,469 listings starting at $23,499
2014 Ford F-150 Lariat SuperCrew 4WD For Sale
25 Great Deals out of 874 listings starting at $14,995

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.