Massey Ferguson - MF188 - Ignition Problem

[Scooter69]

Hi Everyone,

I have an MF188 (Perkins Diesel engine) with an ignition system problem. The ignition system suddenly stopped & my initial diagnosis was that the starter was earthing out.
I took the starter to the auto electricians who confirmed the fault. Replaced the starter/solenoid unit with brand new unit & still no response at all from the starter.
Tested power at the solenoid control terminal with key switch in start position & found 0V from lead referenced to negative when connected, but 12V when the lead was disconnected. Battery tests at 12.8V & was fully charged on charger prior to test.
Tested & bridged safety switch with no response.
Tested with 12V from positive terminal directly to solenoid with no response.
Im now at a loss what else it could be. Could the new starter be faulty?

 

[Jim.ME]

(quoted from post at 06:22:15 11/02/21) Hi Everyone,

I have an MF188 (Perkins Diesel engine) with an ignition system problem. The ignition system suddenly stopped & my initial diagnosis was that the starter was earthing out.
I took the starter to the auto electricians who confirmed the fault. Replaced the starter/solenoid unit with brand new unit & still no response at all from the starter.
Tested power at the solenoid control terminal with key switch in start position & found 0V from lead referenced to negative when connected, but 12V when the lead was disconnected. Battery tests at 12.8V & was fully charged on charger prior to test.
Tested & bridged safety switch with no response.
Tested with 12V from positive terminal directly to solenoid with no response.
Im now at a loss what else it could be. Could the new starter be faulty?

Welcome to the forum.

Where in the wide world are you located? The 188 is not a common tractor to the United States. It is not a model we can see in the on line parts books available from AGCO in North America. You might try posting this down below on the Massey Ferguson and Massey Harris Forum. There might be someone on that forum, familiar with the 188, that hasn't seen this posted here.

It is possible for new parts to be bad right out of the box. Not knowing the manufacturer of the starter you have, I will ask if the lead directly to the starter motor is accessible. If it is I would try using a jumper cable to apply 12 volts to that terminal to see if the starter motor itself turns. (Be certain the tractor is in neutral before trying this.) If the motor turns it would seem the solenoid could be the problem.

 

[JMOR]

(quoted from post at 06:22:15 11/02/21) Hi Everyone,

I have an MF188 (Perkins Diesel engine) with an ignition system problem. The ignition system suddenly stopped & my initial diagnosis was that the starter was earthing out.
I took the starter to the auto electricians who confirmed the fault. Replaced the starter/solenoid unit with brand new unit & still no response at all from the starter.
Tested power at the solenoid control terminal with key switch in start position & found 0V from lead referenced to negative when connected, but 12V when the lead was disconnected. Battery tests at 12.8V & was fully charged on charger prior to test.
Tested & bridged safety switch with no response.
Tested with 12V from positive terminal directly to solenoid with no response.
Im now at a loss what else it could be. Could the new starter be faulty?

ake sure it is in neutral first, then jumper across those two large terminals on the end of the solenoid (wrench or screwdriver works) and see if starter motor runs.

 

[Scooter69]

(quoted from post at 08:50:13 11/03/21)

(quoted from post at 06:22:15 11/02/21) Hi Everyone,

I have an MF188 (Perkins Diesel engine) with an ignition system problem. The ignition system suddenly stopped & my initial diagnosis was that the starter was earthing out.
I took the starter to the auto electricians who confirmed the fault. Replaced the starter/solenoid unit with brand new unit & still no response at all from the starter.
Tested power at the solenoid control terminal with key switch in start position & found 0V from lead referenced to negative when connected, but 12V when the lead was disconnected. Battery tests at 12.8V & was fully charged on charger prior to test.
Tested & bridged safety switch with no response.
Tested with 12V from positive terminal directly to solenoid with no response.
Im now at a loss what else it could be. Could the new starter be faulty?

ake sure it is in neutral first, then jumper across those two large terminals on the end of the solenoid (wrench or screwdriver works) and see if starter motor runs.

Update - turned out that the positive lead was the issue. Carrying volts but not carrying any current. Tricky one, but sorted now.

 

[Steve@Advance]

'Carrying volts but not carrying any current.'

That's why you always test under a load.

Especially when using a volt meter, they are so sensitive it will pick up the slightest voltage, but has no regard for usable current.

Hold the starter switch, turn on some lights, anything to load the system.

 

[Scooter69]

We are in Australia mate!
Got the problem sorted. It was the positive main lead.

 

[JMOR]

(quoted from post at 18:41:56 11/03/21) 'Carrying volts but not carrying any current.'

That's why you always test under a load.

Especially when using a volt meter, they are so sensitive it will pick up the slightest voltage, but has no regard for usable current.

Hold the starter switch, turn on some lights, anything to load the system.

bsolutely! I sure wish more folks understood that! Take a 9v battery, connect one meter lead to neg and hold other meter lead between thumb and fore finger and touch pos battery terminal with second finger and meter reads voltage. A good demo of sensitivity & shows that even a dirty/corroded connection will carry voltage where a sensitive meter is involved.