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Truck won't start-Grounds!

I tested the wires to the starter. Obviously, the large power wire has ~12.5v on battery power. When my wife turns the key to START, I have 0 volts on the ignition wire at the starter. I reinstalled the starter.

I went up to the underhood fuse/relay center and yanked the relay. The contact that pin 30 would fit into has a constant 12v, the contact for pin 85 is a constant ground, the contact for pin 86 shows 12v when the ignition is on START but 0v when the key is at run or off (like it should), and the contact for pin 87 would go to the starter. So far, everything seems normal.

I popped the relay in and tried START again to no avail. The relay clicks but no power goes to pin 87. I tried another relay with the same results. So I took the relay back out and did a jumper wire from the contact for pin 86 to the contact for pin 87. When the key is turned to START, the contact for pin 86 supplies 12v to the contact for pin 87 like the relay would normally do. The starter spun up and I got a lot of smoke out of the exhaust and hocus pocus but the engine never ran. The smoke can easily be attributed to dumping all of that fuel in every time the key was turned to RUN, which has been many times now. I also tried the key in the RUN position and jumping the contact for pin 30 (constant 12v) to the contact for pin 87 (going to the starter) and the vehicle still would not start but I got the starter spinning and a lot of smoke out of the exhaust just like the other scenario. I'm figuring I need to let the motor crank for a while to discharge the fuel dump out of the exhaust and then it will probably fire up, but by this point my batteries were getting weak. I'm on a charger right now.


I'm really curious why I have power going to the contact for pin 86 when the key is in START but the relay won't send power to pin 87 (which leads to the starter solenoid). I tested this with the relay in it's position but slightly lifted up and when the key is in START, the pin for 86 gets power but the relay isn't sending power to pin 87. I've now tried 2 other relays with the same results.


Also, am I right in thinking I need to crank for a while for the engine to begin running because of all of the fuel I keep dumping in or is there another reason why the motor won't start and run?
 
Ok, so I had pin 86 and pin 85 switched around above. Pin 86 is a constant ground and pin 85 gets the power when the key is on.

Now I'm not sure I had things 100% right earlier, but it appears that I have 12+v on pin 85 whenever the key is in the RUN or START position. If that's the case, the relay should send power to pin 87, which would spin the starter basically whenever the key is in the RUN position. I'll verify one more time in a minute.

I did recheck ALL fuses and found nothing amiss. I also replaced IGN-A just to be sure it was good.
 
Iknow I'll get flack for this but what you need to do (takes 2 people) is disconnect the glows and then while the other person is cranking mist an ever so small amount of starting fluid in the intake. On my plow truck I had the same scenario for not starting but it would crank (I bought it like this) I finally figured it was flooded and that's what I did to get it started it would start cranking faster and faster and I kept adding a lil more starting fluid, it finally took off and I had a huge and I mean huge cloud of black smoke out the exhaust. no problems since. Sorry I can't help with the relay sounds like maybe the signal from the ign switch will show voltage but but won't flow enough juice to pwer the relay.
 
Just rechecked the function of the relay. It APPEARS that pin 30 is still constant 12v. Pin 85 is the ignition switched source (RUN or START) which powers pin 86 with 12v via the relay. Pin 87 still goes to the starter and my best guess is that it should be seeing 12v at some point. I don't have a wiring schematic. The contact in the relay center for pin 87 shows continuity to ground. If I take the relay out and jump pin 30 to pin 87, the starter spins the motor.

I have no idea how to proceed at this point.
 
What would make pin 86 have power when the key is in the RUN and START position? Pin 86 should only have power when in START position. Also, why don't I have continuity to ground on pin 85? If I manually ground pin 85 and turn the key to RUN, the starter cranks but the motor never runs.
 
Looks like I'll start tracing wiring on Thanksgiving since I work tomorrow.

It appears I need to follow the yellow wire from the ignition switch to the fuse block in the dash first. If I remove that 10A crank fuse and test there to see if the wire gets 12v when in RUN, then the problem is between the fuse block and the ignition switch. If I only get 12v when in START, I need to move on to the purple wire going to the neutral safety switch.

If I unplug the switch at the transmission I can test purple wire to see if it only gets 12v when the ignition is in START or if it's also 12v when in RUN. If it's only powered under START, then the problem must be in the purple/white wire going to pin 86 for the starter relay in the fuse relay center.

I'm going to take a stab in the dark here and say it's probably going to be an underhood wiring issue simply because I have no ground on pin 85, pin 86 does have continuity to ground (weird), pin 86 is always 12v in RUN or START. Pin 85 gets 12v via the relay whenever the relay is in place and the key is in RUN or START.
 
I'll admit my 6.5 knowledge is limited here. what if you just cut power to the IP so it wouldn't add more fuel while cranking? I know on the DB2's it the pink wire but not sure on the DS4 setup. if you crank it over without more fuel going in, it should clear it out. when/if it tries to start you could reconnect the power.
 
ok here's what I found for the pin numbers.

pin 30 is constant(confirmed)
pin 85 live from IGN switch
pin 86 should be ground
pin 87 goes to the starter.

that's the basic wiring setup for a 4 pin relay.

IGN(yellow) should have 12V before the neutral switch.
you can check the neutral switch but either 12V out(assuming the first part passed) or do a continuity test(might get 12V but not enough amps to do the job, worn contacts) relay clicks but doesn't close it all the way

the lack of ground and pin 86 being live in both run and start is got me puzzled.:???:
 
Pin 85 and pin 86 are reversible on standard Bosch relays. It's simply to close a circuit. Pin 85 on the truck should be ground and pin 86 should be the ignition switched source.
 
ya I missed that one. coils don't care which side is live. did you ever try the gearshift wiggle? put it into neutral and wiggle the gears shift back and forth through the neutral range.
 
you could be getting the voltage but how's the amps look. I admit it's gotten me more than once. think of the OPS issues, 12V but no amps.

you don't happen to have a 12V light bulb with a couple of wire leads kicking around? just a 25 watt bulb or something.
 
I'm sure I could solder some wire to a light bulb and test it. To me, it's sounding a lot more like I have some melted together wires somewhere along the way, likely between the neutral safety switch and fuse relay center.
 
the other spot I hate to say it could be is at the IGN switch. how did the connector/wires look when you changed it? I know it's a PITA to deal with but still a possibility. testing at the neutral switch in run would tell you forsure
 
hope these help
 

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