I have an 802a that I cannot get to crank from the main S1 switch, I only hear the relay clicking from behind the panel, the batteries are fully charged, I cleaned up all the terminals and the ones to the starter. I believe it's in engine shutdown mode, as the idiot light for coolant high temp is coming on preventing it from wanting to crank, but even when I bypass that switch with a jumper wire, nothing changes. Even when turning on the battleshort it still will not crank. The dead crank switch will work but I have to open the throttle manually to get it to start and run and it won't stay running. The CB1 and FU1 are good, I'm not really sure what else to check or whats causing it to go into engine shutdown mode even if I'm bypassing the temp switch with battleshort engaged.
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MEP-802A will not crank (coolant high temp light coming on)
- Thread starter polk738
- Start date
- 17,348
- 25,645
- 113
- Location
- Burgkunstadt, Germany
Pull the plug out of the back of the fault indicator. Try and start it. OH, you did try resetting the fault indicator, right?
- 2,245
- 3,908
- 113
- Location
- Pepperell, Massachusetts
Bypassing the switch by disconnecting the wires and putting a jumper across the two wires will cause a High Temp Fault.
Remove that jumper and leave the wires disconnected and try it.
The high temp switch is OPEN during normal temps and is CLOSED when the coolant temp gets too high.
Yes, I have done both of those already several times still the same result
- 2,245
- 3,908
- 113
- Location
- Pepperell, Massachusetts
Do you have a handheld voltmeter, and do you know how to use it to make DC voltage measurements?
Yes I have done this as well, it still will not crank, and whats strange is the switch reads open when I put my meter to it.
UPDATE: So me an one of my co-workers here in the shop were going through it, he traced back some of the shut-down functions to a diode on TB 4 (it's a black one between terminals 10 and 11 that sits along the wall underneath the top panel, we tested the diode, he determined it as open, so we thought that was the issue so to be sure I swapped it out with another one from another generator that I pulled into the shop, no dice still the same issue. But now, I can't get any power functions at all, nothing turns on, no relay clicks, fuel pump or anything.
Yes, I'm a DOD civilian for the Army Reserves and work in a maintenance shop, I just don't know much about power generation other than basic stuff I have learned over the years working with 3k, 5ks and 10ks as a wheeled vehicle mechanic with the Army.
- 2,245
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- Location
- Pepperell, Massachusetts
CR5 has no bearing on engine cranking. It's just a flyback diode for the FSS.
Test for about 24 volts DC with respect to chassis ground along the following points leading from S1 to the starter with Battle Short OFF, Dead Crank in NORMAL and S1 in START. Be sure the Emergency Off Switch is pulled OUT and circuit breaker CB1 is reset.
1) S17 both terminals (Emergency Off Switch)
2) CB1 both terminals
3) S1 terminals 2,4,6 & 8
4) S1 terminal 7
5) Relay K12 terminal 8
6) Relay K12 terminal 2
7) Relay K16 terminal 9
8.) Relay K16 terminal 6
9) S7 terminal 1
10) S7 terminal 2
11) K2 Terminal X1 (Starting relay in AC compartment)
Relay terminal numbers are embossed in the gray plastic sockets by each terminal.
Post up your findings when you get a chance.
Relay locations...
Be sure leftmost thing in the row of relays (S14) has a circuit board in it and that it's not a relay like the rest in the row
Start signal path in yellow
Test for about 24 volts DC with respect to chassis ground along the following points leading from S1 to the starter with Battle Short OFF, Dead Crank in NORMAL and S1 in START. Be sure the Emergency Off Switch is pulled OUT and circuit breaker CB1 is reset.
1) S17 both terminals (Emergency Off Switch)
2) CB1 both terminals
3) S1 terminals 2,4,6 & 8
4) S1 terminal 7
5) Relay K12 terminal 8
6) Relay K12 terminal 2
7) Relay K16 terminal 9
8.) Relay K16 terminal 6
9) S7 terminal 1
10) S7 terminal 2
11) K2 Terminal X1 (Starting relay in AC compartment)
Relay terminal numbers are embossed in the gray plastic sockets by each terminal.
Post up your findings when you get a chance.
Relay locations...
Be sure leftmost thing in the row of relays (S14) has a circuit board in it and that it's not a relay like the rest in the row
Start signal path in yellow
- 17,348
- 25,645
- 113
- Location
- Burgkunstadt, Germany
Do you get even panel lights?
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- 1,245
- 93
- Location
- Wapakoneta, Ohio
FYI they will never crank with the battle switch on. Like Klopp said above always double check the E stop it gets everyone.
Thank you very much this is extremely helpful, I will check tomorrow morning when I get a chance, I'm off work right now, I didn't know about the circuit board style relay I figured it was just an off brand style, I did switch all the relays around but I'll make sure to switch it back.
I did before I switched the diodes, now I'm not sure but I'll check tomorrow morning.
That's good to know thank you, and yes I've checked the stop switch several times
Good morning so this is what I"ve found after going through all the checks
S17 both terminals: .5 volt (prime & run) & start
23V in off
CB1 both terminals: .5 volt (prime & run) & start
23V in off
S1 terminals 2,4,6,8: .5 volt (prime & run) & start
23V in off
S1 terminal 7: .2 volts (prime & run) & start
0 volts in off
K12 terminal 8: .3 volts (prime, run) & start
0 volts in off
k12 terminal 2: .2 volts (start)
0 volts in prime, run and off
k16 terminal 9: .5 volt in start
0 volts in off
K16 terminal 6: 0 volts anywhere
S7 terminal 1 & 2: 0 volts anywhere
K2 terminal X1: 0 volts anywhere
- 2,245
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- 113
- Location
- Pepperell, Massachusetts
OK, this likely indicates there is high resistance in the path to get power from S10 (Dead Crank Switch) terminal 3 to S17.
So do the same check with the conditions I posted above at S10 terminal 3. If you get about 24 volts with S1 in Prime/Run and Start then there is an issue between S10 and S17. The wiring path from S10-3 to S17 is...
S10-3 to connector P7 pin 14 via wire number 133Axx. Then J7 pin 14 to S17-1 via wire 133Bxx.
(The xx in the actual wire number stenciled on the wires is the wire gauge)
My hunch is there a poor connection or corrosion in connectors P7 and or J7. You'd need to disconnect P7/J7 and examine the pins, clean if necessary, check continuity to the points they go to respectively and then reconnect P7/J7.
S10 terminal 3: 23V in off position .5V in start/run position
I found connector J7, but I can't find P7, where is that located?
nevermind found it, it's underneath
Last edited:
- 17,348
- 25,645
- 113
- Location
- Burgkunstadt, Germany
I would suspect a loose J7/P7 or a pin broken or burnt off.
How do you disconnect these connectors? Does it use some kind of twisting lock ring?
- 17,348
- 25,645
- 113
- Location
- Burgkunstadt, Germany
Simply unscrew it. Grab it with your hand and unscrew it.