tachometer intermitent
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Elder User
Joined: May 2003
Posts: 520
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From: california
tachometer intermitent
I picked up a 1999 Ranger with the 4.0 4x4 auto. Sometimes the tach reads 0 and then sometimes it actually works. I searched the forums and thought maybe the connectors may be corroded. I disassembled the the cluster and found no corrosion at the pins. I can;t see any obvious burns or breaks at the printed circuit board. Is there a way to test that board? Also where does the tach pick up the signal? I'd like to check the connections at that location.
Thanks in advance.
Thanks in advance.
Cargo Master
Joined: May 2004
Posts: 3,007
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My 1999 Ford Service manual (FSM) indicates that after a visual inspection of the circuit board, "if no damage is evident, each circuit should be checked with an ohmmeter. If an open circuit or a short is detected the instrument cluster printed circuit must be replaced."
"The tachometer (17360) is a 5000 rpm tachometer. It has four terminals labeled "B" (12 to 14.5V), "S" (EDIS tach signal in), and two "G" (cylinder selection grounds). The top ground (G) terminal is open on a 4-cylinder vehicle, and is grounded on a 6-cylinder engine vehicle."
"The tachometer (17360) is a 5000 rpm tachometer. It has four terminals labeled "B" (12 to 14.5V), "S" (EDIS tach signal in), and two "G" (cylinder selection grounds). The top ground (G) terminal is open on a 4-cylinder vehicle, and is grounded on a 6-cylinder engine vehicle."
Cargo Master
Joined: May 2004
Posts: 3,007
Likes: 5
test the circuit 398 (black with yellow stripe) at the connector, to ground.
the resistance should be less than 5 ohms
if not repair the circuit
if the resistance is more than 5 ohms then
test the between circuit 11 (tan with yellow stripe) at the connector and the EEC-V 104 pin
The resistance should be less than 5 ohms
if not repair the circuit
If more then
measure the voltage between circuit 11 and ground
should be between 5 and 8 volts
if not then install a new PCM (ouch, hope it's not this)
If it is then test the instrument cluster printed circuit board by
checking resistance between the tachometer and the instrument cluster printed circuit terminals
B terminal and c214-13
S terminal and c214-15
G terminal and c215-2
G terminal and c216-8 (6-cyl)
If the resistance is below 5 ohms on all then install new tachometer and test for normal operation
if not then install new instrument cluster printed circuit.
Don't forget to take pictures and post here.
the resistance should be less than 5 ohms
if not repair the circuit
if the resistance is more than 5 ohms then
test the between circuit 11 (tan with yellow stripe) at the connector and the EEC-V 104 pin
The resistance should be less than 5 ohms
if not repair the circuit
If more then
measure the voltage between circuit 11 and ground
should be between 5 and 8 volts
if not then install a new PCM (ouch, hope it's not this)
If it is then test the instrument cluster printed circuit board by
checking resistance between the tachometer and the instrument cluster printed circuit terminals
B terminal and c214-13
S terminal and c214-15
G terminal and c215-2
G terminal and c216-8 (6-cyl)
If the resistance is below 5 ohms on all then install new tachometer and test for normal operation
if not then install new instrument cluster printed circuit.
Don't forget to take pictures and post here.
Thread Starter
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Elder User
Joined: May 2003
Posts: 520
Likes: 1
From: california
Thanks for the info. I'm a bit lost on some of your instructions when you mention the listed printed circuit terminals. Not sure where they are.
This is the printed circuit board where the tach goes.
This is the back of the tach.
I tested the ohms for the blk/y wire to ground. It read 2.7 ohms.
I didn't know where circuit 11 is located because I couldn't tell which wire was the tan/y. I also didn't know where the EEC-V 104 pin is located. But since the blk/y ohmed out at less than 5 ohms, I didn't think I needed to go to this step.
Still not sure where circuit 11 is located, but will get another set of eyes in the morning so I can test the volts.
I'm not sure where the following terminals are located:
c214-13
c214-15
c215-2
c216-8 (6-cyl)
I checked the resistance at the tach pins as shown in the pics and had the following results:
G to B = 9.02 ohms
G to S = 16.12 ohms
G to CYL = 33.6 ohms
This is the printed circuit board where the tach goes.
This is the back of the tach.
I tested the ohms for the blk/y wire to ground. It read 2.7 ohms.
I didn't know where circuit 11 is located because I couldn't tell which wire was the tan/y. I also didn't know where the EEC-V 104 pin is located. But since the blk/y ohmed out at less than 5 ohms, I didn't think I needed to go to this step.
Still not sure where circuit 11 is located, but will get another set of eyes in the morning so I can test the volts.
I'm not sure where the following terminals are located:
c214-13
c214-15
c215-2
c216-8 (6-cyl)
I checked the resistance at the tach pins as shown in the pics and had the following results:
G to B = 9.02 ohms
G to S = 16.12 ohms
G to CYL = 33.6 ohms
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