I have a SCAG Model STC52V-24HN with a Honda GXV670 TAF2 engine that has a number of issues including a broken connecting rod. I bought a new Honda GXV690 TAF2 as a replacement. Everything bolted in nicely except I cannot get the wiring to function correctly. I am re-using the SCAG harness adapter for the old engine and it seems like the connections to the new engine are a match. However, the engine cranks but I am not getting any spark (i.e., smell of gas and plugs have gas on them when I inspect them.) I am thinking the issue is the wiring adapter? Any thoughts on how to fix this issue would be greatly appreciated.
UPDATE: The folks at Honda corporate office proved me with the following information.
"The GXV670 engine has a ignition coil that uses a ground applied to stop the engine and a open circuit to get spark and let the engine run, the GXV690 engine is exactly the opposite so you will ground the ignition coil to get spark and let the engine run and then remove the ground to get the engine to stop."
They suggested that I contact my regional Honda distributor for specific recommended wiring changes. I am awaiting a reply.
UPDATE: According to the folks at SCAG the open circuit/ground signals to the GXV670 engine are supplied through the interlock module. All the mower safety switches/interlocks are also tied into this module. They offer no updated interlock module for the GXV690.
Firstly check to see if the old coil ca be fitted to the new engine.
If not then pop a relay between the coil and the cut off wire.
The switched circuit on a relay can be + or - and the control circuit again can be full time + with a = wire causing it to switch or full time - with a + causing it to switch.
THANK YOU for your responses.
Yes - the old coils fit in the new engine and this has been my "temporary" fix. I have thought about the adding a relay approach but still not sure exactly how to do it. Are you talking about a 4-pin relay?
THANKS for the additional information. It makes it much clearer. I am going to stick with using the old coils until the end of mowing season. I will work on the relay approach over the winter.
THANKS for the additional information. It makes it much clearer. I am going to stick with using the old coils until the end of mowing season. I will work on the relay approach over the winter.
IF it is running fine then leave it as is.
The fewer parts in the wiring the less there is to go wrong.
pop the coil in a bag/ box with a note and perhaps a relay just in case.
The K.I.S.S. principle is a very sound one.
The old mowers with no relays & interlocks cause way less grief than the modern idiot proof ones.
FINAL REPORT
1. Putting the old ignition coils on the new engine did NOT work. The old coils have BTDC timing of 20 degrees whereas the new coils have 9 degrees. Engine ran but lacked power.
2. Ended up installing a relay to interface between the SCAG system and the "backwards" ignition of the new engine. The SCAG system has a number of safety interlocks and I choose not to disable. On this basis then, the final product works as follows. There is no change to the starting procedure. However, stopping the engine is different. If you turn off the key engine will continue to run for about 5 seconds. Alternatively, if you activate any of the safety interlocks (e.g., parking brake) engine will stop immediately. You have to remember to then turn off the key.
#11
Zimoludek
Hi, I also have the STC52V-24HN with a Honda engine which I like to replace it with a 27HP Briggs & Stratton engine Model 44Q777 Type 3137G5 Code 120723YG. No issue with getting the engine in but I'm a bit confused with the wiring the new engine come with Alternator and Started build in it also doesn't have the throttle but that's just one less cable to connect. The Honda had the solenoid next to started so I will need to get the solenoid and install it on the SCAG frame I get that but now wiring.
