Toyota 7FGU30 No crank/No start please help

[WaelB]

Hello folks, I have a 7FGU30 that's been giving me fits. Let me try and explain the behavior and some of the steps already taken.

No crank
No start

Checked all grounds, all fuses, all relays. All test fine.
When starter relay contact terminals are jumpered, it will crank but will not fire. Tested voltage at starter relay coil terminals and not getting ground to the ground terminal of the relay coil when start switch cranked. The strange part is when trying to crank, I actually get a positive 12vdc to both coil terminals of that relay but no ground. Checked for broken or damaged wires but did not find any.

Regulator solenoid seems to be getting power as I can hear it click when trying to crank. When spraying starter fluid into the air box and jumpering the starter relay contacts, it cranks and sounds like it wants to start but never does. So I'm at least getting spark.

Both the no crank and no start issues happened at the same time so I feel they are likely related. I may be way off here but I am suspecting possibly an ECU issue. There is an ECU underneath the left foot step with a part number of 24610-U2201-71 that a mechanic friend suggested to swap out and try but I really don't know what this ECU is responsible for and I would rather just not throw parts at it without being fairly confident that this is the issue.

I would really appreciate some guidance with this. I'm just at a point where I feel totally defeated.

 

[Coaldust]

The seat safety switch is probably on the fritz. Check the easy stuff, first.

 

[WaelB]

We did have problems with the seat safety switch in the past but I did not think that would actually prevent it from cranking?

The issues we had with the seat safety switch was it would sporadically prevent operating the levers/hydraulics and the seat light would also sporadically illuminate. One of our guys disconnected it and jumpered the two wires together. This solved the problem for about a day but then the seat light started to flash. So I reconnected it as it was intended originally.

However, can the seat switch cause a no crank? In the past we have always been able to start the machine while nobody seated in the seat.

 

[Coaldust]

Welcome to the HEF, BTW. I had some 7FGU30 units I took care of at a petroleum warehouse. I don’t recall them being able to crank unless a butt was in the seat. I could be wrong.

I would try and rule that out, before you spend anymore time troubleshooting.

 

[WaelB]

I agree. I will look closer at that.
How do you suggest I troubleshoot the seat switch? I know when you sit in the seat, the instrument light goes off. When you raise your butt off the seat, the light comes on. So I assume it must be working. Is there another way you would suggest to verify that?

 

[Simon C]

I agree. I will look closer at that.
How do you suggest I troubleshoot the seat switch? I know when you sit in the seat, the instrument light goes off. When you raise your butt off the seat, the light comes on. So I assume it must be working. Is there another way you would suggest to verify that?

If you can get a schematic for the machine, we could more likely help you.
Simon C

 

[WaelB]

Hello Simon, this is what I have.

 

[Simon C]

Hello Simon, this is what I have.

Only thing I missed is whether it is gasoline, Diesel or propane as different schematic each, but looked at and decent schematic. Please respond.
Simon C

 

[WaelB]

Hi Simon, my lift is propane only. Also it is a single speed. No EZ-pedal if that helps

 

[Simon C]

Hi Simon, my lift is propane only. Also it is a single speed. No EZ-pedal if that helps

Thanks will look and see if I can suggest anything simple.
Simon C

 

[WaelB]

Thank you Simon

 

[Simon C]

Okay so you have no crank and no start.

#1 Go to the starter relay and it has a large wire coming into it (White/Blue I believe ) and going out to the starter solenoid by means of a large black wire.-----Check for 12Volt power with a meter at the wire coming out of the relay with your red meter lead while your black meter lead is on battery Negative and someone else holds the key in the start position. If you do not have around 12 volts there the relay is junk, or the source feeding it is faulty( 40 amp fuse ) or the control circuit is not working to excite the relay.

#2 Check at same relay on the coil side to see if there is power to the positive side of it with key held in the start position ( It is a black wire smaller in size coming from the Shift controller ST- Terminal ) and goes to ground.
Is there power here?

While key is held in Start position how far does voltage go down with Red lead on Battery Positive. and Black lead on Battery negative.

Lets start with these tests.
Simon C

 

[WaelB]

#1 yes I have 12v positive on the contact side of the starter relay. I can get it to crank by jumping the two terminals on the starter relay socket but it will not start. Relay is good. Tested it out of circuit.

#2 yes there is +12v on the coil side of the relay but no ground on the other side (this is the problem).

Voltage does not drop at all or at least very much when holding in start position and testing for voltage drop across battery terminals. A few fractions of a volt maybe.

 

[Simon C]

If you have power on the ground side of the coil of the Starter Relay but no path to ground then you will have to follow it in the harness and repair or hook another wire to it and hook it to a good frame ground. If it cranks after that but does not start we can deal with the separate problem.
Simon C

 

[WaelB]

I will try to explain this next experiment I did as best as possble.

Testing the two terminals of the coil side of relay socket with the key in the #1 position but not cranking I get the following results.

Left side side terminal = ground
Right side terminal = ground

When holding key in crank position both these terminals go 12v positive. When one Shem should go ground in order to energize the relay but this is not happening.

When performing the same experiment on a working lift, I get the same readings except when cranking, one goes ground.

By the way, I need to clarify that the above testing is done with the relay itself removed.

This is the odd part. What is giving the ground terminal a path to positive 12v? Seems to me that an ECU must be controlling this.

 

[WaelB]

We did pull the fuse/relay box out and tied in a ground directly to the coil terminal that should be ground. It did crank but would not start

 

[Simon C]

I will try to explain this next experiment I did as best as possble.

Testing the two terminals of the coil side of relay socket with the key in the #1 position but not cranking I get the following results.

Left side side terminal = ground
Right side terminal = ground

When holding key in crank position both these terminals go 12v positive. When one Shem should go ground in order to energize the relay but this is not happening.

When performing the same experiment on a working lift, I get the same readings except when cranking, one goes ground.

The ground side of that coil of the Start relay is actually positive until it gets inside the negative post of the battery, and is more so if the wire going to ground is broken completely. If you don't understand go to your car and disconnect the negative post and hold onto cable up in the air,, have your wife go turn key to start position and hold it there. The second you touch that negative cable on the negative post there will be a major arcing and maybe top of battery will blow off. All power is positive until it enters the negtive post when there is a disconnect before the negtive post. Don't try this unless you have a long stick to tie cable to, cause you will have an explosion.


Now if you get it cranking but no start, we need to see if the power is going to the LPG Relay & LPG Solenoid.

Hope you understand what I explained about positive until it enters the battery. But if battery negative connection is good you can take a wrench from battery negative to frame ground and should have only tiniest or no spark, not an explosion like above.
Simon C

 

[Simon C]

Hope I did not confuse you as the small wire being disconnected to Ground is what causes the confusion for people. Hope it helps.
Simon C

 

[WaelB]

The ground side of that coil of the Start relay is actually positive until it gets inside the negative post of the battery, and is more so if the wire going to ground is broken completely. If you don't understand go to your car and disconnect the negative post and hold onto cable up in the air,, have your wife go turn key to start position and hold it there. The second you touch that negative cable on the negative post there will be a major arcing and maybe top of battery will blow off. All power is positive until it enters the negtive post when there is a disconnect before the negtive post. Don't try this unless you have a long stick to tie cable to, cause you will have an explosion.


Now if you get it cranking but no start, we need to see if the power is going to the LPG Relay & LPG Solenoid.

Hope you understand what I explained about positive until it enters the battery. But if battery negative connection is good you can take a wrench from battery negative to frame ground and should have only tiniest or no spark, not an explosion like above.
Simon C

Yes thank you Simon. I was not aware of that. I will pass on that battery experiment for now but I’m sure one day I’ll give it a shot. It would be interesting.

So at this point it seems there may be a damaged wire. So I will go ahead and try to trace that wire. As for the no start, I can hear the solenoid click on the LPG regulator when trying to crank. I’m not aware of an LPG relay specifically but I did remove and test all the relays I could find and they all tested good. Do you by chance know where this relay would be located?

 

[WaelB]

No you didn’t confuse me. Your explanation was clear and thorough and has educated me to some things I did not know