Power but no cranking

[sgauvry]

Gents -

Having a problem with my 1985.5 F150 5.0 EFI. I am unable to crank the engine.

Battery presently has about a 13.7 amps. Possibly, more amps are required to crank the engine?  

There's a new starter solenoid, and connections are correct (positive battery cable and 4 wires to the "M" stud, starter wire to the "B" stud, red wire to the "S" stud).  

I can hear the high pressure fuel pump briefly engage as I turn the key.

Relay switches worked fine with the old engine and harness.  I know that doesn't necessarily indicate they are working correctly, but I am assuming they are.

Fuel gauge, emissions light, and battery charge light work.  

The wire harness is good and I have it connected correctly.  The only exceptions I can think of may be the alternator connections (will double check those to ensure they are correct) and the pigtail terminal from the battery that connects to a connector that runs to the EEC and grounds the entire system. I have some work to do on that to make it a great ground.  

I'm not wanting to actually start the engine at this point.  Although it's been primed with oil using a dummy distributor rod, but I want to crank it a bit to make sure oil is circulated very well and that any trapped air can escape. Can't get it to crank.

I know I'll have to do some diagnostics, but not sure where to begin. As always, I appreciate the sound advice I get here!

Steve

[Gary Lewis]

You should be able to force it to crank by connecting a small jumper from the hot terminal on the starter solenoid/relay to the small terminal that should have a red/light blue wire on it.  Remove the r/lb wire and jumper to that terminal and the engine should crank - but don't be standing in front of the truck!

[sgauvry]

Yes!  Following your suggestion, it cranked.  

What next?

[Gary Lewis]

Good!  But, are you asking me what the next problem will be?  Or, how to troubleshoot the problem?

[sgauvry]

How to troubleshoot.  

[85lebaront2]

Steve, I seem to recall that is an AOD, is the back up lamp/neutral safety wiring plugged in, it may have two connections, one on the transmission and one possibly near the transmission crossmember to frame bolts on the driver's side.

[sgauvry]

Everything is connected.  Doesn't AOD refer to the tranny?  In that case mines a C6.  

[sgauvry]

I suppose it's time to do a voltage drop test.

[Gary Lewis]

Yes, AOD is the tranny.  But C6 will have the same connections.

You need to use pages 29 and 30 here (1986 EVTM/Start) and use your volt meter to find the problem.  The R/LB wire comes from the ignition switch on Page 29 and goes to Page 30 via the blue M triangle.  Then it goes through the neutral safety switch and back to Page 29 via M.

However, if you don't have the truck in neutral or Park it won't crank.

[Gary Lewis]

No, not yet.  That's to find bad connections.  You probably have a disconnection or maybe you don't the tranny truly in Park or Neutral.

[sgauvry]

Bill - I'll look for those connections.  They don't sound familiar.  

[sgauvry]

I looked for connections.  I found the following as shown in the two photos:





There is also a connection that comes from those shown in the photos and runs along the frame parallel with the gear shift mechanism on the tranny, and is connected to a wire that runs to the gear shift mechanism.  


All are connected.  The vehicle is in park.  I shifted around between gears from park to lower 1 gear and back.  Still no cranking.  

[Gary Lewis]

Did you have the key in Start while you shifted between gears?  (Be very careful there.)  If so, then even if the registration is off between the shift lever and the transmission itself you should have at least passed through Neutral and it should have cranked.

Now you need to do that testing I was talking about.  I'd start with the R/LB wire at the transmission.  Disconnect the wiring from the transmission and put the red wire of your meter to one of the pins and the black wire on a good ground.  Put the meter on the 20 volt scale and turn the key to Start.  You should see 12v, but if not you may have gotten the wrong pin, so use the other pin in that connector and you should see power.

If you don't see power/12v on either pin when in Start then the problem is between there and the ignition switch.  If you do see power/12v on a pin then the problem may be downstream from there.  But it may also be in the transmission switch.  So jumper between the two pins and see if it will crank - but watch what gear you are in as there's now no neutral safety switch.

[sgauvry]

Will do, Gary.  Unfortunately, we're getting snow today and tomorrow and it's getting too wet and cold to do that now.  But I will do what you suggest as soon as it's a little drier and warmer, hopefully in a few days.

Thanks!!

Steve

[Gary Lewis]

Hope you don't get too much snow.  We need the moisture, but it seems to be going well north of us and it'll be 56F this afternoon with a bit of sun.  So I hope to get my winch wiring done.

Anyway, take care.  And don't worry, I'm sure it is a simple problem.  You just have to track it down.

[sgauvry]

Thanks for the good wishes.  I'm sure it'll get worked out.

What I'd give for 56F today...

Steve

[sgauvry]

One other question regarding the no crank issue.

I modified the harness slightly by extending the wires to the TFI module connector so as to reach the module which I have mounted remotely in a heat sink.  Although I took great care in soldering connections and ensuring I reconnected the correct wires correctly, it is possible I did not.  If wires were connected incorrectly, or came disconnected, that could cause my no cranking issues, couldn't it?

[Gary Lewis]

Yes, it is possible.  On Page 29 you can see that the R/LB wire goes to the TFI module.  So if it were connected to a ground or some huge load that the ignition switch can't support then that could cause it.

[sgauvry]

Thanks!  I saw the link to the TFI module in my trouble shooting manual on the pages your recommended.  I'll check those connections as well once the weather breaks.  

[sgauvry]

Hi Gary -

So we have about 10 inches of very wet snow on the ground.  If it had been colder, we'd have had much more than that since it snowed continuously for about 36 hours.  

Anyway, I'm mostly dug out and I tested the plug nearest the transmission (located along the rail).  There is exactly 12v coming from it.  So that tells me all connections (at least to this point) are good. However, I did not remove the wires from the tranny to test them and I had forgotten about jumping the two pins to see if it cranks.  

When I disconnect the wires from the tranny, are there only two pins?  If there are more, what two pins are you referring to?

Steve