OT-90 / BMP - Does Not Start - Looking for Suggestions

[Timberwolf22]

So we were working on the OT-90 the other morning and she started right up. Packed up some things and shut her down.

Today we went to start her and ...... nothing.

First steps - check the batteries - 12.3v on each battery and 24 volts across both - looked good. We always seem to have an issue with that dog-bone cable that links the two batteries so I made sure it was on tight and not melted (different story) Started to follow the power and the relay for the started looked good as well.

We check fuses - I pulled checked and cleaned every fuse in the battery compartment. We then checked the fuses in the drivers compartment - found a 10amp fuse in the drivers dashboard that was blown - replaced but no change in starting.

So what happens is when you thrown the main power switch in the dash (far right) you get lights in the dashboard as normal however when you then engage the pre-oiler (oil pump) switch - nothing not enough power (or some other reason) that the oil will not engage. When you try your bilge pumps same result. You can hear them click but no engagement and dashboard lights will dim.

When you then try and start the vehicle with the two - air and electric push buttons = nothing. No started noise or engagement.

I have been tracing wires all day looking for a bad ground or broken wire in the path to the started or solenoid but nothing so far. I disconnected every battery terminal .... cleaned and then rewired = no change. I put on a 24v jump pack just incase the batteries needed help = no change.

So far our guess is a bad ground or a blown component in the system but we can't seem to locate yet and while I sit here reading my TM I figured I might as well see if anyone had any fresh ideas.

Thanks in advance.

 

[B3.3T]

90% of the time, what you describe is the result of a bad ground. Check or run new grounding.

 

[Timberwolf22]

So an update on the OT-90

Spent the night going thru the TM specifically the sections on electrical systems for the OT-90.

This morning we went down and pulled both batteries out of the vehicle. I cleaned all the terminals and then rewired everything - tested voltage at the batteries 12.4 in each battery and 24.9 across them both.

When the batteries were out I had much better access to the battery section and took the opportunity to clean out that area in the back of the crew compartment.

After I was finished with the rewiring - changed out a few ground cables as well I asked for a 2nd set of eyes to check my work.

Guess what he found.........



Yep all the way back in the fuse box .... and I swear it was not that obvious - he agreed but noticed it when he was crawling around checking the ground wires.

So this is not just a fuse you have lying around. There are three of them two are 100amp and the 3rd is 80amp. So we pulled the other 100amp and moved it over to the blown fuse receptacle and she fired right up!

So now I need to check the TM as to what I lost without the 2nd 100amp fuse in place and then find a place to get a few spare.

So what did we learn today - Always have someone check your work - 2nd set of eyes!

 

[kcimb]

Great job! The most frustrating problems can be caused by the smallest parts.

 

[SETOYOTA]

Glad you got her going. Owning a foreign made odd vehicle can be dufficult. I have a british fv432. It has been a great vehicle but I often feel like I’m one small problem away from owning a 15 ton paper weight.

glsd you found your issue.

 

[Robin33ba07]

Glad you got her going. Owning a foreign made odd vehicle can be dufficult. I have a british fv432. It has been a great vehicle but I often feel like I’m one small problem away from owning a 15 ton paper weight.

glsd you found your issue.

hello there I have an OT90 in Ireland ,did you get the fuse issue fixed ? I have some spares I got years ago if you can send me a picture of the fuse you want I might be able to help you out ? regards Robin

 

[dmetalmiki]

You CAN make up a new fuse set up using modern 80-100 amp fuses from a modern car. We did.
Perfect, and spare fuses readily available. We have 100s from scrap vehicles.