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Hey guys, hoping you all can help me make some sense of what just happened. So the vehicle in question is a 1988 Bronco (so basically an F-150) and the original issue was that the vehicle could no longer be started with the key. Everything electronic works in the RUN position (fuel pump, dash lights, radio), but turning to START would do nothing. Truck could be started by jumping the solenoid, but no power was getting to the activation wire on top of the solenoid. Got the ignition switch out from on the column under the dash and determined that it was functional, when it was moved to START power was being transmitted through the red/light blue wire that runs to the starter solenoid. HOWEVER we were not getting power to the R/LB wire after it passed through the C202 (?) round connector through the firewall. Installing a jumper from the R/LB as it leaves the ignition switch plug out through the firewall and connecting to the R/LB in the engine bay harness, and the truck will start and run fine. Do people usually run into issues with the round connector in the firewall? I find it curious that the ignition switch functioned normally EXCEPT for the starting circuit. Truck is working now with the jumper wire still in place, should I leave it like that or how should I go about getting this wiring issue fixed?
Another sort of related, sort of unrelated issue. Before tearing down the truck, the truck would only start in the PARK position and the engine could only ever be shut off in the PARK position. Now, the truck will start in every gear and can be turned off in every gear. Do the 8th gens have a sort of "safety" that prohibits starting in gear and if so, where is that mechanism located? Grandpa seems to think adjusting the ignition switch on the bottom of the column (under the dash) might have something to do with it, I personally can't see that having an effect on it. Either way, the truck is fixed but this has certainly been an interesting issue and I'm hoping to hear others' thoughts regarding the questions I've posed.
Normally there is some kind of inhibitor switch to prevent you from starting the engine in gear. On a manual, it's a clutch switch. On an auto, it's a park/neutral switch. Not sure if that's on the column or on the trans on these rigs. It should be wired between the key switch and the solenoid (it breaks the circuit when you're not in park or neutral).
Whether it's worth fixing depends on how comfortable you are without it. My dad's '87 had a clutch switch, and it was shot, so we bypassed it. If you hit the starter in gear with the clutch out, you'll feel it lurch immediately, and we're used to driving older manuals with no interlocks, so we're not worried about it. On the other hand, my friend ran her clapped-out Toyota into the back wall of her garage after we bypassed the inhibitor (push-button start wired straight to the starter motor because the key switch was worn and not worth the cost to replace properly). Autos take a moment to grab. Also, if that inhibitor switch has other functions (like telling the trans computer what position it's in), you could be in for more issues in the future as that switch craps out.
The Neutral Safety Switch is located on the driver side of the transmission. It's function in life is to prevent you from starting the engine unless the transmission lever is in the Park or Neutral position. It also contains the switch for the reverse lamps.
Normally there is some kind of inhibitor switch to prevent you from starting the engine in gear. On a manual, it's a clutch switch. On an auto, it's a park/neutral switch. Not sure if that's on the column or on the trans on these rigs. It should be wired between the key switch and the solenoid (it breaks the circuit when you're not in park or neutral).
Whether it's worth fixing depends on how comfortable you are without it. My dad's '87 had a clutch switch, and it was shot, so we bypassed it. If you hit the starter in gear with the clutch out, you'll feel it lurch immediately, and we're used to driving older manuals with no interlocks, so we're not worried about it. On the other hand, my friend ran her clapped-out Toyota into the back wall of her garage after we bypassed the inhibitor (push-button start wired straight to the starter motor because the key switch was worn and not worth the cost to replace properly). Autos take a moment to grab. Also, if that inhibitor switch has other functions (like telling the trans computer what position it's in), you could be in for more issues in the future as that switch craps out.
Yeah I know what you mean. I always thought it was something in the key switch that prevented the vehicle from starting in gear, but it very well may be the NSS, as Randy mentioned. I have no problem bypassing it, as the vehicle should be shut off and started only in Park and I'd like to think my little brother will be aware of this fact. Thankfully this is a C6 so no computer shifting issues to deal with.
Originally Posted by rla2005
The Neutral Safety Switch is located on the driver side of the transmission. It's function in life is to prevent you from starting the engine unless the transmission lever is in the Park or Neutral position. It also contains the switch for the reverse lamps.
Thank you for providing the location of the NSS Randy. I'm wondering if the switch went bad and is preventing the vehicle from cranking no matter the gear. As I said, we ran a jumper basically from the ignition switch plug to the underhood harness to get the vehicle to start, thus we may have bypassed the NSS circuit, no matter whether it is good or bad.
You might wanna take a look up under the dash at the ignition switch attached to the column or even the starter solenoid on the fenderwell..
Have you tried using a multimeter to see if the start wire for the solenoid shows voltage when the key is turned....
This is what can happen when they go bad
Thanks for the advice Surge. We did pull the ignition switch, clean it up and test it, verifying that it was working fine. No burn marks on it like the photo you provided. Also confirmed with a test light that when moved to the START position, it was sending power through the Red/Light Blue wire which runs to the solenoid. Also confirmed the solenoid is working, as jumping the small post to the battery side will allow the vehicle to start. What was confusing me was power was not getting to the R/LB as it came through the firewall into the engine bay.......
What we ended up doing was running a jumper wire attached to the R/LB wire coming out of the switch and splicing it into the R/LB in the engine bay harness. Upon doing this, the vehicle will start normally with the key. The issue I have been having is, now, the truck will start in any gear. That, and I'm not sure if our jumper setup is safe to continue using, or if it will cause any other electrical issues further down the line.
As others have stated, the next thing I plan on checking is the Neutral Safety Switch attached to the transmission, as it is responsible for interrupting this START circuit if the vehicle is not in PARK or NEUTRAL. It's possible that the switch is bad and not allowing the circuit to close, no matter what gear the vehicle is in.
Moving forward, I intend to get the pinout for the NSS plug and jump the leads that connect the circuit. Then, AFTER disconnecting our jumper wire, see if the vehicle will start. If so, that should point to the NSS being bad.
There is no resistance. The contacts are either open or closed for the start circuit. Same for the reverse circuit.
Good to know Randy, thanks. Would jumping the plug work instead to confirm the switch is bad, and if so do you happen to have a pinout for the NSS plug?
Good to know Randy, thanks. Would jumping the plug work instead to confirm the switch is bad, and if so do you happen to have a pinout for the NSS plug?
Most Neutral Safety Switches for a C6 have 4 wires. The start circuit wires are usually Red/Light Blue into the switch and back out. Some years the start wire coming from the ignition switch may be White/Pink. The other two wires are for the backup lamps. Usually Purple/Orange is the power feed, Pink/Black is the power output to to the backup lamps when the the transmission lever is placed in Reverse.
If you happen to have the 6 pin NSS, the Red/White wire comes from the electronic 4wd shift module, the other contact goes to ground. Not sure on the wire color.
Can you tell what color your wires are, I see 2 threads, one has pic
Originally Posted by rla2005
Most Neutral Safety Switches for a C6 have 4 wires. The start circuit wires are usually Red/Light Blue into the switch and back out. Some years the start wire coming from the ignition switch may be White/Pink. The other two wires are for the backup lamps. Usually Purple/Orange is the power feed, Pink/Black is the power output to to the backup lamps when the the transmission lever is placed in Reverse.
If you happen to have the 6 pin NSS, the Red/White wire comes from the electronic 4wd shift module, the other contact goes to ground. Not sure on the wire color.
Randy and torq'ta - thank you both for sticking with me on this one. Sorry I haven't done much work. The truck is my brother's only form of transportation and he's at work most days, which makes it tough to find time to tear it apart. I'll relay soon what we find, though I believe it is a 4-wire plug.
yours isnt, E4OD, didnt see in signature, until I read again!
