Community Forums

turboeclipse · 10-28-2022, 03:09 PM

I have a 1997 Tioga Montara ford E350 V10 that is not charging the coach battery when the engine is running. The isolator relay works fine but the ignition wire connection has zero volts when the ignition is on. I traced the wire back to the fire wall but can't seem to find where it ends up. Is it a fused connection in the instrument panel fuse box or in the power distribution fuse box? Thanks

twinboat · 10-28-2022, 03:38 PM

My 1999 E450 tapped a ignition wire out under the hood. There was a fuse in a covered inline holder near the radatior shroud.
If your wire goes inside, there are taps in the Ford fuse box under the dash.

CharlesinGA · 10-28-2022, 07:02 PM

Quote:

Originally Posted by turboeclipse

I have a 1997 Tioga Montara ford E350 V10 that is not charging the coach battery when the engine is running. The isolator relay works fine but the ignition wire connection has zero volts when the ignition is on. I traced the wire back to the fire wall but can't seem to find where it ends up. Is it a fused connection in the instrument panel fuse box or in the power distribution fuse box? Thanks

Not doubting that you are not getting power on the ignition circuit, but you say the relay works. Did you apply power to it and it went "clunk"? If so, did you start the engine and determine that current was passing thru the relay?

I say this because these relays are notorious for burning up the contacts. They operate fine, but don't pass any current. Should you need to replace the relay, I suggest you use the Cole Hersee 24213

https://www.amazon.com/Cole-Hersee-2.../dp/B005K2429I

This relay is rated at 200 amp continuous (the original ones are generally 80 amp) and this has Tungsten-Silver plated contacts. You merely have to add a ground wire ton one of the small winding terminals.

Charles

turboeclipse · 10-28-2022, 07:18 PM

The bypass switch works fine. The relay thunks when I hit the switch and the the coach battery and cab battery are then at the same voltage. When I release the switch the coach battery goes back to its lower voltage. The switch and ignition wire are connected to the same terminal on the relay. So the relay is good. Thanks.

turboeclipse · 10-29-2022, 10:38 AM

Unfortunately I have been unable to locate a connection into the instrument panel fuse box or power distribution box. All the fuses are accounted for except for one modified vehicle fuse which isn't it. The picture shows where the purple ignition wire enters the harness which goes along the back of the engine compartment where it merges with the main harness. I have not been able to locate an exit point or obvious external fuse.

THenne1713 · 10-29-2022, 05:46 PM

Where do you think this Isolator RELAY is on yours? On MINE, (99 chassis) BOOST= Under Coach step and CHARGE= FIREWALL FORWARD OF DRIVER. If your have Boost confused w/ Charge, that wud explain no power to coil?

THenne1713 · 10-29-2022, 06:37 PM

FUSE #15 (5A) UNDER DASH panel labeled "TRAILER BATTERY CHARGE RELAY" may feed CHARGE relay coil?

turboeclipse · 10-30-2022, 09:37 AM

Thanks guys! I checked the number 15 fuse in the instrument panel fuse box and it is good as well as the Trailer battery charge (relay) in the power distribution fuse box. I'll try to buzz the connections out with a volt/ohm meter.

turboeclipse · 10-30-2022, 12:10 PM

Unfortunately none of those items tie into that circuit. I just bypassed it with a switch, fuse, and relay tied into the dash illumination fuse. Now I can switch it on or off anytime I want. Maybe some day I'll figure it out. Thanks for the help.