Wait light stays on, crank but no start.

[Mogman]

Yes, next step will be to check voltage and then ohm out the plugs.
There is a IP diode that was destroyed, burnt and cut in half. Would this have anything to do with it?
What is this diode for?

The IP diode shunts reverse EMF to ground, if it is burned in two then it is no longer effective but is also not interfering with the operation of the IP.
Not all HMMWV's have this diode (as shown by the dotted lines) so it is not essential for operation.

 

[4x4Junkie13]

Update,


I left this alone for a weekend and am now back on it. I am trying to track down what wires should have constant power going to the start box. I don’t think this problem has to do with anything else other than wiring

Would the master start switch have constant power? (11A/B)



This is my start box connector outline for reference.

571 A/B: Wait light

67A/B: Brake warning lamp switch

14B: Neutral Safety Switch { goes back to Master start switch}

27C/B: 15 amp CB (Run Power 1) { goes to 27D fan switch}

57B: Ground for Horn switch

15A: Light switch

11A/B: Master Start Switch

29C/B: Ground 15 amp CB (Run Power 2) { goes to 29A/B Master Start Switch

 

[4x4Junkie13]

Also to address the other questions from before there is zero voltage going to the glow plug wires so that is why I am going back to chasing wires.

 

[86humv]

11 a/b constant volt
15A constant volt
54A from inj pump to 54B on start box eng conn.
29C from start sw. to Start box body conn.

 

[4x4Junkie13]

11 a/b constant volt
15A constant volt
54A from inj pump to 54B on start box eng conn.
29C from start sw. to Start box body conn.

I am not clear on from what you are saying. The 54A->54B, you say it goes to the start box but that is not the case. There isn’t a 54B going to the start box on the inside where my wires were cut. I checked for continuity on 54B going to the solenoid and it is good.

 

[86humv]

54B is on the eng. side connector pin A at start box.
54B goes through start box....and out through pin B wire 29c of body harness to start switch wire 29 A.

 

[4x4Junkie13]

I decided to pull all the cut wiring apart and start over from scratch.
tone tested each wire to its component and found that I connected 571 and 57B and at least one other incorrectly.
got it all sorted and am now soldering them back together to make clean lines again.

New issue:
Voltage gauge seems to overcharge (go into the red) with quick blips of the throttle.
Tach didn’t seem to come on at first while the volt gauge said it was in the yellow,
Then the tach kicks in and the voltage goes into the green but goes into the red if you quickly hit the throttle.

 

[Mogman]

The tach uses the A

I decided to pull all the cut wiring apart and start over from scratch.
tone tested each wire to its component and found that I connected 571 and 57B and at least one other incorrectly.
got it all sorted and am now soldering them back together to make clean lines again.

New issue:
Voltage gauge seems to overcharge (go into the red) with quick blips of the throttle.
Tach didn’t seem to come on at first while the volt gauge said it was in the yellow,
Then the tach kicks in and the voltage goes into the green but goes into the red if you quickly hit the throttle.

The tach uses the AC terminal from the reg. for the RPM input, if the alt is not charging the tach will not work.
Put a VOM on the batteries or alt output and see what is really going on, curious if you hold high RPMs does it go back to green?

 

[4x4Junkie13]

The tach uses the A

The tach uses the AC terminal from the reg. for the RPM input, if the alt is not charging the tach will not work.
Put a VOM on the batteries or alt output and see what is really going on, curious if you hold high RPMs does it go back to green?

Yes sir, it drops back into the green if I hold the rpm’s.
I was thinking it sounds like a loose connection or perhaps a bad ground.

 

[Mogman]

Yes sir, it drops back into the green if I hold the rpm’s.
I was thinking it sounds like a loose connection or perhaps a bad ground.

Have you tested the batteries? with a good set of relatively charged batteries the voltage should not change, the alt should produce enough at idle to reach the 28.2V or so that it normally charges at.
Checking all grounds is a good idea on any truck
This is a 200A alt?
Have you checked the idle RPMs, if it was idling too slow I could see the alt dropping out then "kicking" back in when you raise the RPMs
Does the meter read the same at idle as it does with steady high RPMs?, this is an interesting issue..