L2900 electrical issues

[mulberryG]

hello everyone, new to the forum, need some help. i've got an late 90's L2900 w/1500 hrs that i bought brand new. been very dependable until about a year ago. i noticed the glow light indicator would stay on for a longer and longer times. then it started staying on the whole time the engine was running. then the battery would die down over night. thought i had a bad battery, so popped a new one in, it died overnight. charged it back up, cranked it and checked alternator. was only putting out 12 vt. thought that was low, so took it to alt shop, they bench tested it, putting out 14.5. when i hooked every thing back up, i noticed a significant arc on the + as i touched clamp to the post.

this indicated i had a power drain. got out the dc amp clamp meter. it showed a 29 amp draw for about 15-20 seconds, then drops to 15 amps. all of this with the key turned off. only way to control it is to pull 40 amp fuse by the starter.

pulling the fuses one at a time doesn't do anything. so no help there.

given by issue with the glow plugs, i'm thinking that is a symptom of my problem.

any input would be appreciated
thanks

 

[Jim L.]

I think that I would disconnect the key switch, and at the same time watch the dc ammeter. If the current goes to zero, then I would ohm the switch to verify that it is bad.

 

[85Hokie]

that many amps ....seems to me that the contacts in the switch that control the glow plugs are staying closed, thus the light on the dash and the huge amp draw.

What if you discontented the wire going to the glow plugs, if you have not, try it and see if the amp draw is still there.

report back!

 

[mulberryG]

thanks for the quick response. will try both suggestions. just got back from the dealer, they also were stumped. ive isolated the amp draw to the small red wire leaving the starter and going through the 40 amp fuse. dealer indicated that this wire is what feeds the dash and fuse block.

does anyone know of a schematic drawing of these electrical systems. all dealer had was a print out of the parts manual showing exploded view

as far as i can tell, the only thing hot with no key in the ign is the switch assy and the starter.

thanks

 

[lugbolt]

Glow plug system is got something going on. The system can draw more amperage than the little alternator puts out, thus when checking the charging voltage, it will show "low"...making one think that the alternator is dead.

It's not uncommon for the glow relay or the glow timer to die. The system is automatic, reading a signal from the coolant temp sensor mounted on the engine. With cold coolant, it's supposed to hold the glow plugs on longer, hot engine, just a second or less. When the relay or timer dies, normally the contacts get stuck (welded) and the glow plugs are "on" all the time, kills the battery, draws more than the alternator will put out, and wears on the wiring due to continuous high amp draw. Pick up a WSM and check the glow plug system and it's diagnosis. Good place to start based on what I'm reading.

 

[mulberryG]

good call, lugbolt. just got in from chasing wire. constant 15 amp draw on the glow plug harness. even with the key switch out of the loop. in the printout from the dealer, i see a key timer relay and a glow plug relay, i'm guessing thats the components your referring to.

WSM? Is that a service/shop manual? is that a dealer item or can i read it online somewhere.

one good thing to come of this is finding this site,
thanks again

 

[85Hokie]

good call, lugbolt. just got in from chasing wire. constant 15 amp draw on the glow plug harness. even with the key switch out of the loop. in the printout from the dealer, i see a key timer relay and a glow plug relay, i'm guessing thats the components your referring to.

WSM? Is that a service/shop manual? is that a dealer item or can i read it online somewhere.

one good thing to come of this is finding this site,
thanks again

Mulberry,

WSM is the Work Shop Manual and sounds like your relay is closed and staying that way.

 

[mulberryG]

BINGO, it was the glow plug relay. pulled it out of sequence and the 15 amp load went away. key off, .14 amps, key on .45. not sure of normal,but this seems in specs.

thanks again for the spot on advice and suggestions.

hokie, i noticed you highlighted the control module also. is this one of those"as long as your there, you should change it also" kind of things.

thanks again

 

[mulberryG]

well, got one thing fixed, another one pops up. changed the glow plug relay and controller, no more dead battery overnight, But, now, the starter relay just clicks when i try to start. i did a search and found a schematic and bench test for the relay. i think mine is ok, but i did find the red wire was loose in the spade connector. i pulled it out and re crimped a new connector in. thought that would fix it , still not working.. cleaned all connections and grounds

anything i didn't think of?