Tach question.
Lead Driver
Joined: Mar 2006
Posts: 5,111
Likes: 1,544
From: western SD
Case IH Guy, Welcome to the IDI forum. As you have changed the sensor, check the wiring harness for any chaffed wires. I has been reported just unpluging the harness from the back of the gauge cluster, and plugging it back in will sometimes cure the no tach issue.
Logistics Pro
Joined: Sep 2010
Posts: 4,411
Likes: 4
From: Victor, MT
Farmert, while you are right, these Tach sensors can be bad from the factory, or they will work forever. I would take the tach sensor out of the oil filler neck/ip gear cover and clean it, these tachs are magnetic and will attract shavings and whatnot....
New User
Joined: Mar 2012
Posts: 10
Likes: 0
I am not trying to hijack thread, but I am having similar problem, could you explain a little better about the oil filler neck/ip gear location of the tach sensor, I want to try cleaning mine up to see if it will work all the time, not some of the time.
Senior User
Joined: May 2010
Posts: 288
Likes: 0
From: Oregon
the part where the wire comes through the firewall can have a bad connection, and the gauge can also have a bad ground -
I have both going on, push clutch in and sometimes it stops working or only halfwayish. Also hit the lights and it changes about 100rpm.
I have both going on, push clutch in and sometimes it stops working or only halfwayish. Also hit the lights and it changes about 100rpm.
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Logistics Pro
Joined: Sep 2010
Posts: 4,411
Likes: 4
From: Victor, MT
It can also be your alternator messing with it, i know I dont have one in the 84 motor i just swapped in and the wires will pick up the pulses from your alt....
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New User
Joined: Mar 2012
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The truck that this is happening too is an auto, I got the truck and the front axle just got replaced so I haven't drove it yet. Will this effect the shifting with it not picking the tach sensor? FYI, I have the stuff to switch to a manual.
Lead Driver
Joined: Mar 2006
Posts: 5,111
Likes: 1,544
From: western SD
The 94 should have the E4OD tranny, so yes it will effect how the tranny shifts. I'm not an auto guy, but I believe it will through the tranny into limp mode, and it will kill the tranny if you drive it much without getting it fixed.
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New User
Joined: Mar 2012
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The truck isn't a daily drive. So it will sit till its fixed. Plus I'm making a new harness for the glow plugs too. The manual is what I'm wanting just don't have the time for the swap. Work has got me swamped at this point (love my job, it comes first). So hopefully I won't have to work Sunday and I'll be able to work it on.
This will be me fourth zf 5speed truck when the tranny swap is done. And my 3rd diesel. First 6.9 idi banks turbo, 94 PSD, now 94 idit. I'm excited to get this truck going. My First crew cab.
This will be me fourth zf 5speed truck when the tranny swap is done. And my 3rd diesel. First 6.9 idi banks turbo, 94 PSD, now 94 idit. I'm excited to get this truck going. My First crew cab.
Posting Guru
Joined: Aug 2004
Posts: 2,417
Likes: 4
From: Braham MN
If the sensor is bad it will effect the trans shifting, if the tach in the dash is bad it shouldnt bother the trans at all. take it for a drive and if it shifts bad you know its not the gauge, if it shifts fine, you know the tach pick-up is good....
Diesel Rod
Diesel Rod
Senior User
Joined: Sep 2008
Posts: 318
Likes: 1
From: Portage Des Sioux, Mo
I had a problem with my sender. Tach worked sometimes was erratic others. Seemed to be wet weather triggered. Turned out to be wires were they went into sender had bad insulation. I used some liquid eletrical tape at the entrance to sensor and have not had a problem since.