Won't lockup at certain RPM?

flyboy912 · 08-15-2008, 09:15 PM

My 98 1/2 5.9 has an auto tranny. At 45-47 mph it goes in and out of lockup constantly changing the rpm. At 50mph or so it locks up and is OK after that. Does anyone have an idea what is doing this?

Last edited by flyboy912 : 08-15-2008 at 09:18 PM.

**patracy** · 08-15-2008, 09:26 PM

Yep, common issue due to noise over the signal.

1. remove the batteries.
2. Clean all the connections.
3. Calibrate the APPS voltage (do a search)
4. Reset the APPS (search)
5. Test

If that doesn't work....

A. Try wrapping the ground lead from the alt. with foil to shield it.
B. Install a TC lockup switch. (Search in the tech forum, I've made a thread)
C. APPS re-wire.

__________________
1999 2500 4x4 Club Cab Sport. ADRENALINE/pulse , BHAF, FBD 150 sticks, full set of gauges, FP light, Holley Blue pump, 1/2" big line kit, Draw straw, 3" glasspack, TC lockup switch, Stealth VP plate, Heated WVO setup, poor man's 'pane setup, BD TC, BD VB, Billet input, Derale pan.
Parts to come: turbo and bigger exhaust, both seriously needed now!

08-15-2008, 09:15 PM	#1 (permalink)
flyboy912 Newbie Join Date: Aug 2008 Posts: 1 flyboy912's Truck Pics	Won't lockup at certain RPM? My 98 1/2 5.9 has an auto tranny. At 45-47 mph it goes in and out of lockup constantly changing the rpm. At 50mph or so it locks up and is OK after that. Does anyone have an idea what is doing this? Last edited by flyboy912 : 08-15-2008 at 09:18 PM.

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08-15-2008, 09:26 PM	#2 (permalink)
patracy GA Chapter Vice President Join Date: Oct 2007 Location: Buchanan, GA Posts: 1,627 patracy's Truck Pics	Yep, common issue due to noise over the signal. 1. remove the batteries. 2. Clean all the connections. 3. Calibrate the APPS voltage (do a search) 4. Reset the APPS (search) 5. Test If that doesn't work.... A. Try wrapping the ground lead from the alt. with foil to shield it. B. Install a TC lockup switch. (Search in the tech forum, I've made a thread) C. APPS re-wire. __________________ 1999 2500 4x4 Club Cab Sport. ADRENALINE/pulse , BHAF, FBD 150 sticks, full set of gauges, FP light, Holley Blue pump, 1/2" big line kit, Draw straw, 3" glasspack, TC lockup switch, Stealth VP plate, Heated WVO setup, poor man's 'pane setup, BD TC, BD VB, Billet input, Derale pan. Parts to come: turbo and bigger exhaust, both seriously needed now!