tach not working
Thread Starter
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Cross-Country
Joined: Aug 2000
Posts: 61
Likes: 1
From: Cincinnati, OH
tach not working
2000 F350 V10 - just noticed the other day that the tach is not working. I looked thru my Haynes manual and I have one of the $25 service manual CDs.....nothing I can find on the tach at all.
I need to check out the simple stuff first, like loose wire, connector, etc. Where is the sensor for the tach? What else should I check for?
Thanks.
I need to check out the simple stuff first, like loose wire, connector, etc. Where is the sensor for the tach? What else should I check for?
Thanks.
Logistics Pro
Joined: Jan 2002
Posts: 3,733
Likes: 38
The dash mounted cluster is a smart device-- in other words it takes signals from several sources and conditions the signals to make the gages and meters read what you see
You motor does not has a distributor nor a direct RPM tach signal from any one sensor that goes directly to the tachometer (the PCM creates the tach signal for the dash cluster from signal it MUST have from the cam position sensor and a few other places to make the motor run)
I assume the truck is running properly
If so, then some where between the PCM and the Dash cluster you have a signal loss...or it may be that the dash cluster is hosed up....
Getting to the back side of the dash cluster can be a real pain
did you recently have an remote start or security system installed?
Hacked up wireing can cause this as they usualy splice into the tach wire under the dash
If all other things on the dash are working... (hint the entire dash goes through a self test on start up key turn) the you need to find the tach wire and see if it is broken
no I do not know the color of the wire ---it changes year to year on these beasts.
Ask down in the electrical forum or the radio forum and see if someone has recently work on the tach wire for same year truck as yours
You motor does not has a distributor nor a direct RPM tach signal from any one sensor that goes directly to the tachometer (the PCM creates the tach signal for the dash cluster from signal it MUST have from the cam position sensor and a few other places to make the motor run)
I assume the truck is running properly
If so, then some where between the PCM and the Dash cluster you have a signal loss...or it may be that the dash cluster is hosed up....
Getting to the back side of the dash cluster can be a real pain
did you recently have an remote start or security system installed?
Hacked up wireing can cause this as they usualy splice into the tach wire under the dash
If all other things on the dash are working... (hint the entire dash goes through a self test on start up key turn) the you need to find the tach wire and see if it is broken
no I do not know the color of the wire ---it changes year to year on these beasts.
Ask down in the electrical forum or the radio forum and see if someone has recently work on the tach wire for same year truck as yours
Thread Starter
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Cross-Country
Joined: Aug 2000
Posts: 61
Likes: 1
From: Cincinnati, OH
Fredvon4,
Thanks. There has been no modifications. The truck runs fine. The only thing not working is the tach. I know the tach wire would be in a harness with other wires. The other wires could go to some of the idiot lights on the dash. I'm not sure which of these would light up for a moment at start-up so I don't know if these are working or not. Could be something simple like the connector is loose. You mentioned the cam position sensor... isn't there a crankshaft position sensor, also? I think you're right about the signals from these. If these were bad or the wire came off of these, the engine may not run, or at the least I would get a Check Engine Light. I'll post in the electrical forum and see what I get. Thanks.
Thanks. There has been no modifications. The truck runs fine. The only thing not working is the tach. I know the tach wire would be in a harness with other wires. The other wires could go to some of the idiot lights on the dash. I'm not sure which of these would light up for a moment at start-up so I don't know if these are working or not. Could be something simple like the connector is loose. You mentioned the cam position sensor... isn't there a crankshaft position sensor, also? I think you're right about the signals from these. If these were bad or the wire came off of these, the engine may not run, or at the least I would get a Check Engine Light. I'll post in the electrical forum and see what I get. Thanks.
Logistics Pro
Joined: Jan 2002
Posts: 3,733
Likes: 38
Lo
On the back side of the master fuse panel down by your left knee there is a box attached to the back of the fuse panel called a GEM (General Electronics Module) I would remove the bolts holding the Fuse panel to get access to the GEM and remove and re insert each electrical connector same for each of the connectors on the back of the master fuse panel
The I would disconnect and re connect every other electrical connector under the dash including behind the steering column cover plates. I would remove the dash cluster and remove and reconnect it's connector(s) and pay close attention to any burnt or discolored "Traces" on the back of the cluster (you will See what I mean if you remove the cluster)
You might get lucky and by accident get the tach working again if it just happens to be a weak, corroded, or loose pin in a connector....if you see burnt traces on back of the cluster you need to decide if replacement cluster is worth just getting the tach back working...I am sure it is a very expensive part even from a junk yard
If you do find a used or new one the dealer can program it for correct odometer setting
On the back side of the master fuse panel down by your left knee there is a box attached to the back of the fuse panel called a GEM (General Electronics Module) I would remove the bolts holding the Fuse panel to get access to the GEM and remove and re insert each electrical connector same for each of the connectors on the back of the master fuse panel
The I would disconnect and re connect every other electrical connector under the dash including behind the steering column cover plates. I would remove the dash cluster and remove and reconnect it's connector(s) and pay close attention to any burnt or discolored "Traces" on the back of the cluster (you will See what I mean if you remove the cluster)
You might get lucky and by accident get the tach working again if it just happens to be a weak, corroded, or loose pin in a connector....if you see burnt traces on back of the cluster you need to decide if replacement cluster is worth just getting the tach back working...I am sure it is a very expensive part even from a junk yard
If you do find a used or new one the dealer can program it for correct odometer setting
