need wiring schematic for white ZT

[38racing]

17BK2ACP090
Friend who I assume took this in on a trade asked me to check it over because he likes his shop people to work on the big stuff. It wouldn't start crank and I traced it to a blown fuse. Now I have traced the fuse blowing to the engaging of the PTO. I have downloaded the operator's manual and 2 IPLs, one from MTD Canada and one from Outdoor distributors. None have the schematic. I have a service manual from
http://support.mtdproducts.com/app/answ ... ExbQ%3D%3D

which has a very good diagram but it does not match the unit or IPL. Reason I say this is that this service manual shows the seat switch has a single pole push button switch that passes 12v to relay(s). The unit has the common pair of metal spring contacts which complete a circuit to ground when off the seat. Trying to decide which end of the circuit to start at but would like the exact schematic. This schematic does provide some insight as to the neutral switches and reverse safety switches operation. I do notice that the wires to one reverse side switch have been cut. Since they carry 12v maybe a patch job is grounding. PTO can engage when either one or both switches are closed. Need to look closer.
Really be great if some had the correct schematic for this unit. Can't call MTD until Monday

[38racing]

So I think I have narrowed it down. The seat setup is not a factor in the fuse blow. The PTO switch has 3 pairs of terminals. first pair is normally closed and is in the cranking circuit and that works ok. The other 2 are NO and closed on switch engagement. One of these closes in a circuit from the engine magneto kill terminal to ground (including seat switch) so has no impact on the 12v fused circuit. The other one of these pairs is in a circuit :battery +->solenoid post->fuse->keyswitch B->keyswitch e (in run)->pto switch 1(in)->pto switch 4(out) (when switch on)->rh and lh reverse switches (in parallell) and ->pto clutch (if either or both reverse are closed). So that is my problem circuit. I checked the LH reverse and its 2 wires have been cut and jumpered together and taped so look ok. I am going to separate those 2 wires and unplug the connector of the RH side. That means no current beyond to the clutch. So if the fuse blows it's from a ground in the wiring to these switches and if not then from either 1 of them to where they join to feed the clutch or the clutch itself. So now for the part I didn't mention before. Friend said it would not start normally but would when boosted direct to starter but then he said it would not move either. So the not moving is a messed up hydro drive belt in the vicinity, of course, to the wiring to the clutch. Unfortunately I cannot really get at it because it's on his trailer and backed against the front panel and be darned if I can find the hydro release levers so I can push it forward. Maybe I can resolve that in the morning. If I can isolate which blue wire is which on these reverse switches I should be able to measure clutch impedance but I suspect that reading will be zero due to the grounded circuit.

[Arkie]

I've collected an assortment of miniature DC breakers that I use for locating short circuits in eq. so as I'm not replacing blown fuses when trying to locate overloaded or intermittent short circuits.
(1 amp to 15 amp) and I also use a UEI model DL49 clamp on meter to monitor DC amps. (0-400 amps self ranging)
Ebay has several sizes of miniature DC breakers and Napa has few.

For intermittent overloads where several circuits are involved and only one fuse getting blowed I've had to place lower amp breakers into individual circuits so as to get idea of which circuit is the culprit. Sometimes for example I rig a 12v bulb[size=200] across[/size] the breaker contacts on 12v circuits and when the breaker opens due to short circuit the bulb immediately lights indicating the overload or short is still present and the breaker is open.

[38racing]

Found the short. After pulling out the mangled belt I found the plug connector to the clutch leads. Wires are bared right at the connector. Not sure how to get tabs out so for now I have made spade end leads to plug into the clutch lead and then will cutoff bad plug and spice feed wires to my leads. In planning the belt replacement it seemed engine pulley groove was higher than the idler/tension pulley and if eyes don't deceive me also higher than the hydro pulleys. I'm thinking the engine pulley is upside down as there appears to be more shaft below belt section than above so reversing it would lower the pulley

[38racing]

No way pulley was coming off. put new belt on and with tension pulley now further away lineup looked better .ran fine but when i engaged PTO the fuse blew. then irecalled that i had put in 7.5 amp fuse for planned circuit test . replaced with 20 and all is well .

[stienut13]

Hi 38,

Nice to see a happy ending! Oops, can I say that here? Anyway, nice job and updates.

Jim

[KE4AVB]

If your using a 20A fuse you still need to do an amp draw test. Your alternator will not keep your battery charged if the PTO is pulling more than it can supply.

I have had several partially short PTO coils to blow the normal 7.5 amp fuses but still worked at higher amp draws. One intermediately showed battery discharge and one other kill the battery after 30 minutes; mower was still mowing until I shut the engine down and attempted a restart.

[38racing]

If your using a 20A fuse you still need to do an amp draw test. Your alternator will not keep your battery charged if the PTO is pulling more than it can supply.

I have had several partially short PTO coils to blow the normal 7.5 amp fuses but still worked at higher amp draws. One intermediately showed battery discharge and one other kill the battery after 30 minutes; mower was still mowing until I shut the engine down and attempted a restart.

20 amp is the correct rated fuse according to the manual. 7.5 was there just because that's I was going to test circuit paths with and no plan to engage clutch with it. Just with age the brain fades and I forgot to replace it. with a 20. Took me an hour tonight to find where I had put my watch.