'98 FL60 Exhaust brake problem???

Question

Wife and I have a '98 FL60 which tows our fifth wheel all over Pacific NW. Last year we developed a problem of intermittent sudden power loss when exhaust brake is engaged. Its been diagnosed by local mechanic as wiring harness problem who referred use to Cumins who applied their computer and said all was well. Less than an hour on the road, and we had a loss of power which we 'cured' by turning off the exhaust brake switch. Again saw a local mechanic who thought the problem was a sensor in Allison transmission. Allison checked and said "no such sensor in Allison".

About that time I had severe heath problems and we spent the whole summer in Boise. Drove the rig home without using the exhaust brake, without problem. Now preparing for travel once again and would like to fix the problem. We are currently in Gilbert, AZ. Does anyone have suggestions? I have spent nearly $1000 and the only solution is 'turn off exhaust brake.'

Thanks

RickF

boogie_4wheel · Answer

What triggers the exhaust brake to engage? Throttle Position switch (release throttle and it triggers a small limit switch on the pedal to complete the circuit)? I'd be looking in to whatever triggers the brake to engage.

What Allison should have told you is that the World Controller (assuming you have one) does have the ability to accept an input when the EB is active to select a lower gear automatically, and the transmission will auto-downshift to keep the engine revved and the brake supplying a higher amount of braking horsepower. Your truck may or may not have this feature.

On a International 4400 (DT570/Allison combo), when the EB was on and throttle released, the transmission controller selected 2nd gear (shown in the display), and as speed slowed the transmission downshifted to keep the engine revved to apply more braking force.

45ricochet · Answer

boogie_4wheel wrote:What triggers the exhaust brake to engage? Throttle Position switch (release throttle and it triggers a small limit switch on the pedal to complete the circuit)? I'd be looking in to whatever triggers the brake to engage. What Allison should have told you is that the World Controller (assuming you have one) does have the ability to accept an input when the EB is active to select a lower gear automatically, and the transmission will auto-downshift to keep the engine revved and the brake supplying a higher amount of braking horsepower. Your truck may or may not have this feature.On a International 4400 (DT570/Allison combo), when the EB was on and throttle released, the transmission controller selected 2nd gear (shown in the display), and as speed slowed the transmission downshifted to keep the engine revved to apply more braking force.X2 I'm not familiar with your vintage but I'd be looking also at the throttle position switch. I've heard of it even on newer MH's. You might also trace down the wiring for rodent damage.  I actually had it happen on my old Ram with the cruise control not working because the brake pedal not realising all the way up. I am assuming you have a exhaust brake and not a engine brake.

ke6irj · Answer

There is a Freight liner dealer in Chandler area.  We use them for our commercial motor coaches.  See you can can accurately recreate the issue, then take them for a ride.  They have been good to us.

jim-linda · Answer

We have an earlier model FL60 w/ Cat. There is no "throttle position" switch, the throttle position is sensed by a variable resistor. When sensor sees "0" position, it will enable brake, and as stated, select lower gear that the program is looking for. I believe an Allison shop will hook up 'puter and with you driving, go for a spin, tech will monitor...monitor for signals. This should pinpoint issue.

Jim

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'98 FL60 Exhaust brake problem???

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