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I have a 1988 Mustang LX with a 5.0 motor and I have been trying to find someone to repair the instrument cluster in it, which has been unsuccessful. I also have tried to find out what parts I would need to repair it myself but have been not been able to find out this info either. Does anyone know what the gauge motors part numbers are and where they can be purchased and also does anyone have a schematic drawing of the 88 instrument cluster they would be willing to email me? The gauges have been acting up for a good while and I am needing to get them fixed especially the oil pressure and fuel level gauges. Any information you can provide me will be greatly appreciated.
 

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I have a 1988 Mustang LX with a 5.0 motor and I have been trying to find someone to repair the instrument cluster in it, which has been unsuccessful. I also have tried to find out what parts I would need to repair it myself but have been not been able to find out this info either. Does anyone know what the gauge motors part numbers are and where they can be purchased and also does anyone have a schematic drawing of the 88 instrument cluster they would be willing to email me? The gauges have been acting up for a good while and I am needing to get them fixed especially the oil pressure and fuel level gauges. Any information you can provide me will be greatly appreciated.
Have you checked the instrument cluster voltage regulator? There's also a module for the fuel level gauge.
 

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Have you checked the instrument cluster voltage regulator? There's also a module for the fuel level gauge.
I agree with mhuggler.
Its also called the "anti slosh module".The part is expensive ($90) so most people just go to the pull-a-part & grab a used module to fix the issue.Its mounted to the backside of the cluster & really easy to remove.Its pictured below.There are two different modules between year models(87-89 & 90-93)so make sure you get one from the correct year range(87-89) The module should be the same whether its a 2.3 or 5.0,just make sure to choose the right year range for your application(87-89)The link below gives a little more info about it.

One other thing to check is the secondary ground,which is the ground strap located between the cylinder head(rear)& the driver side firewall.Make sure its tight & corrosion free at both ends.Sometimes when this ground is bad,turning electrical components on at the dash will cause the temp gauge to increase.
https://www.npdlink.com/store/products/amplifier_assy_instrument_cluster_gauge-186511-2457.html

If you need trouble shooting procedures to verify whether its the module,sender,gauge,ground or other wiring thats bad,click the following link then scroll down to Jrichker's "fuel gauge trouble shooting procedures" and start reading.In my honest opinion, he's probably the most experienced Stang guru there is on StangNet,so his methods are the Mustang bible when it comes to trouble shooting.
http://www.stangnet.com/mustang-forums/threads/what-fixed-your-fuel-gauge-87-93.852376/
 

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Discussion Starter #4
I agree with mhuggler.
Its also called the "anti slosh module".The part is expensive ($90) so most people just go to the pull-a-part & grab a used module to fix the issue.Its mounted to the backside of the cluster & really easy to remove.Its pictured below.There are two different modules between year models(87-89 & 90-93)so make sure you get one from the correct year range(87-89) The module should be the same whether its a 2.3 or 5.0,just make sure to choose the right year range for your application(87-89)The link below gives a little more info about it.

One other thing to check is the secondary ground,which is the ground strap located between the cylinder head(rear)& the driver side firewall.Make sure its tight & corrosion free at both ends.Sometimes when this ground is bad,turning electrical components on at the dash will cause the temp gauge to increase.
https://www.npdlink.com/store/products/amplifier_assy_instrument_cluster_gauge-186511-2457.html

If you need trouble shooting procedures to verify whether its the module,sender,gauge,ground or other wiring thats bad,click the following link then scroll down to Jrichker's "fuel gauge trouble shooting procedures" and start reading.In my honest opinion, he's probably the most experienced Stang guru there is on StangNet,so his methods are the Mustang bible when it comes to trouble shooting.
What fixed YOUR fuel gauge? 87-93 | Mustang Forums at StangNet
I have not checked the instrument cluster voltage regulator, should it have a 12 volt output, or something different? I have checked the anti slosh module and it seems to be good. I know that it is not just the fuel gauge that doesn't work, it hardly ever leaves the empty mark, the oil pressure gauge also has issues, when you are driving it shows a reading and then when you stop in traffic or at a red light you can see and hear the oil pressure needle turn counterclockwise and peg out. I would like to find the part number for the gauge motors and see if I can locate some of them and try them to see if they would help. I could also use a schematic drawing of the instrument cluster if anyone happens to have one. I am going to check the ground wires that you mentioned. I really appreciate any information or suggestions anyone can give me to help me get this problem fixed.
 

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I have tried all of what you have suggested and still have have problems with the gauges working. I also upgraded to LEDs to replace the old instrument bulbs and they seem to be working well. I also have noticed that the Tachometer has stopped working since I put the cluster back in, anyone have any suggestions to what I may or may not have doen that would cause the Tach to stop working? I appreciated any help you can provide.
 

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The following link is a pdf showing the instrument cluster harness connectors.
Page 1 is for the 90-93 model & Page 2 is for the 87-89 model.
The schematic at the bottom shows how the circuit is laid out,but unfortunately the layout shown only matches the wire colors/pin locations for the 90-93 model,
eventhough the schematic is labeled for 87-93 models.It still gives you somewhat of a visual to go by though.

http://www.stangnet.com/tech/cluster87-93.pdf

After more research,the last Mustang equipped with an IVR (instrument voltage regulator) was in 1986,so the 87+ didnt come with one.They did come with an
"anti slosh module" though.The module is attached by a screw on the 87-89 model and is inserted into a slot on the back of the cluster on the 90-93 model.

If none of the gauges work,I would look at the wire that is shared by all of the gauges,such as a 12volt or ground wire.On the 90-93 model,fuse #18 feeds the gauges,but Im not sure on the 87-89 model.
 

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Hey man, I really appreciate the information and the schematics will help out greatly. I had been looking for the schematics on the instrument cluster but did not find anything. I have a lot of experience in electrical and electronic work, that is what I went to school for and the only type of work I have really done, but without the schematics it makes it a lot harder to figure out correctly. I haven't had much time to work with my Mustang, but I am going to start putting a lot more time in it and get it where I can drive it. I will let you know what I find.

Just one more quick question that you might know, the power rack and pinion steering rack has been leaking and I want to replace it, when I call to see about the assembly they ask if it has a 1 piece or 2 piece bushing and also want to know if the car has the performance or standard suspension. I am the original owner and the rack has been changed once before but it has some tire rub and I don't know if the correct rack was installed or not. It is the LX model that came with the optional 5.0, so that makes me think the performance suspension, but I do not know. I also know that the auto parts stores list a 2.25 and a 3.0 lock to lock assembly which puts another question to what was originally in the car. Do you know how I would tell if the car has a standard or a performance suspension on it? Any help will be greatly appreciated.

Thanks again man
 

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The 5.0 LX & GT came with the performance suspension while the 2.3 LX came with the standard suspension.There were 3 racks in total.

(2.3)
Turns= 3.0
Ratio= 20:1

(5.0)
Turns= 2.25/2.50
Ratio= 15:1

The 15:1 rack uses the 2 bushing design,which means youll need 4 rack bushings in total if youre replacing them..

The po probably installed a 4cyl rack he got from a junkyard which has 3.0 turns,so your tires are hitting the fender because the wheels are turning too sharp due to the extra .75 turn.
 
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Discussion Starter #9
I really appreciate the good information. I kind of thought that the 4 cylinder would have the standard suspension and the 8 cylinder would have the performance suspension. I also thought that the wrong rack was put in it when I had it replaced a long time ago, that would explain the tire rub because the 4 cylinders had smaller tires on them. Now I know to get the correct rack, 15:1 to replace the leaking one. I also like the way you explained about the bushings and I cannot tell you how much your help means, hopefully one day i will be able to return the favor. Once again thanks for your help and I will let you know how things turn out as I fix them, and I plan on working on it this weekend and putting your information to go use!
 

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I agree with mhuggler.
Its also called the "anti slosh module".The part is expensive ($90) so most people just go to the pull-a-part & grab a used module to fix the issue.Its mounted to the backside of the cluster & really easy to remove.Its pictured below.There are two different modules between year models(87-89 & 90-93)so make sure you get one from the correct year range(87-89) The module should be the same whether its a 2.3 or 5.0,just make sure to choose the right year range for your application(87-89)The link below gives a little more info about it.

One other thing to check is the secondary ground,which is the ground strap located between the cylinder head(rear)& the driver side firewall.Make sure its tight & corrosion free at both ends.Sometimes when this ground is bad,turning electrical components on at the dash will cause the temp gauge to increase.
https://www.npdlink.com/store/products/amplifier_assy_instrument_cluster_gauge-186511-2457.html

If you need trouble shooting procedures to verify whether its the module,sender,gauge,ground or other wiring thats bad,click the following link then scroll down to Jrichker's "fuel gauge trouble shooting procedures" and start reading.In my honest opinion, he's probably the most experienced Stang guru there is on StangNet,so his methods are the Mustang bible when it comes to trouble shooting.
http://www.stangnet.com/mustang-forums/threads/what-fixed-your-fuel-gauge-87-93.852376/
Do you know for sure that the anti slosh module is available? I'm assuming you are referring to the NPD part in their catalogue. It has been indicating that the part is not available for some time now. I'd order one in a second if it was.
 

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Ford has discontinued the production on the 87-89 Anti slosh module in 2001.
 
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