Speedometer issues- Mom's pickup

Does it have spark? And other questions...

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Speedometer issues- Mom's pickup

Postby dpuckett » Wed Jun 28, 2017 8:07 pm

Working on my mom's pickup. 92 D350 was 518 auto, now Getrag conversion. Speedo worked fine for a few years after the conversion. The last few years it has worked intermittently. So far I have checked the following.

1) Mechanical stuff coming out of transmission. All is in good working order- VSS, ratio adaptor/reducer, drive gear on tailshaft is tight, driven gear is in the correct place with good teeth.

2) VSS verified good in my pickup truck.

3) i have checked wiring to the PCM. All is in good shape.

4) wiring behind gauge cluster is good.

5) I swapped gauge cluster into my pickup a year or so ago for a test drive. Worked flawlessly.

6) leads me to believe somewhere in the PCM the signal may be getting lost. About 2008-09, in the course of a few months, she lost all pcm controlled functions- AC, voltage regulation, OD engagement (hence, the 5spd swap), cruise control. But the speedo worked for awhile after that. I'm stumped. Ideas?
His- 93 W250 club cab LE, auto to Getrag conversion, piston lift pump, 3.54 LSD. 400k+
Hers- 04 QC 4x4. Built auto, Triple Dog, Air Dog. Funny Round truck that aint so quiet.
dpuckett
14mm rotor
 
Posts: 2196
Joined: Wed Jan 03, 2007 4:33 pm
Location: Perryville MO

Re: Speedometer issues- Mom's pickup

Postby matthewh » Wed Jun 28, 2017 11:57 pm

Any chance its the crank sensor? Had a 91.5 that had this issue. Sensor was crapping out, would charge/not charge, slip in and out of OD, etc. Was winter, so no idea if the A/C was working, but I remember the speedo dropping off as it wasn't charging.
Kinda shotgunned parts at it when it happened. Was pretty sure it was the crank sensor, but being winter and my plow rig, threw on everything new besides the pcm, and tested the alt. New crank sensor, all 3 relays, etc.
'93 W350 5spd Getrag, 4.10 gears, 83k miles and counting, Mods: LPPP AKA Ma Dually
'54 Dodge M37 6.2/700R4/205, 5.89 gears, WC rear axle
matthewh
14mm rotor
 
Posts: 627
Joined: Mon Feb 18, 2013 3:07 am
Location: Boyne City Michigan

Re: Speedometer issues- Mom's pickup

Postby dpuckett » Thu Jun 29, 2017 9:08 pm

Volt gauge shows it to be charging, but I'll check it with my multimeter. It got a new CPS from Cummins right before the 5 spd swap.
His- 93 W250 club cab LE, auto to Getrag conversion, piston lift pump, 3.54 LSD. 400k+
Hers- 04 QC 4x4. Built auto, Triple Dog, Air Dog. Funny Round truck that aint so quiet.
dpuckett
14mm rotor
 
Posts: 2196
Joined: Wed Jan 03, 2007 4:33 pm
Location: Perryville MO
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