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dreaded gem module


Trevor_t2

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Ford Ranger
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Forgive me if this has been asked before, I am new here. I have a 1998 ranger which has had ongoing issues with what I believe to be the gem module. My wipers, auto windows and now dash lights are being affected. I initially bought a used module from an auto wreckers and swapped it out. It caused my speedo to zoom right to max and it seemed like my fuel was being limited; it ran like shit with no power. I then bought a $400.00 new one from the dealership and had same problems so I returned it. I asked the guy at the dealership if it needed to be reprogrammed or something, he asked the mechanic who evidently said no. They wanted to get me in the shop and start charging me big bucks without offering any ideas as to what the problem may or may not be. It sounded like I was about to get fleeced so I went on my way. I plugged the old one back in and everything worked fine?? It was like this all summer until the rainy season hit again with a vengeance this week and now my problems are back. I now am convinced it is the module and is somehow caused by moisture cause it was early spring and wet when all this began. My question is, I can get another one but didn't have any success the first time with switching it out (caused other problems as mentioned earlier) and I would like more guidance from someone who has experienced this problem themselves before throwing away my hard earned money (seriously, I can't afford to spend thousands on this truck) so any advice would sure help guys, thanks in advance for your input.
 


Sasquatch_Ryda

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The GEM must be configured to the vehicle using fords scan tool.
 

Trevor_t2

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So if I go back and get the module, plug it in and take it to the dealership they can configure it for me using their diagnostic machine and scan tool? I assume then that they are not simply interchangeable. Why the heck did they seem so vague the first time around, this seems straight forward enough and it could have saved me a ton of headache...
 

adsm08

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Why the heck did they seem so vague the first time around
They may have been worried that if they did configure the module for you and it didn't fix your problems that you'd come back at them saying they did something wrong and try to get them to fix it for you.

I know it sounds ridiculous, but I have seen people try it more than once.


Not sure why they would tell you it doesn't need programmed to work right though. That guy was probably just an idjut.
 

Trevor_t2

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I called another ford dealership today and asked more questions. They said that for 1998 the module should be a plug and go swap out, that reprogramming shouldn't be necessary for that year? He said there was 3 different modules depending on which model truck I own and asked for the numbers off the original module if I was to order a new one. As I cannot GUARANTEE this hasn't been a problem with previous owners, I'm wondering if the module currently in there now was a replacement one (and not the original) that needed to be programmed when IT was installed? At least that would explain why when I plugged in a new replacement that it wasn't configured properly for the truck? Out of all this, I think I will invest in the diagnostic charge for them to at least confirm or deny that it is in fact the gem module. If they tell me they believe it is, then I see no option but to buy one, plug it in and have them spend the time reprogramming it or figuring out why it creates different problems. Try as I might, it looks like I am going to be at the mercy of the dealer; God help me.
I sincerely appreciate your comments, thank you.
 

Sasquatch_Ryda

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Well, seeing as how the shop manual for a 98 ranger states that it is a programmable module right in the re and re steps....

Module—Generic Electronic (GEM)/Central Timer (CTM)

Removal

  1. CAUTION: Electronic modules are sensitive to static electrical charges. If exposed to these charges, damage may result.

    NOTE: The generic electronic module (GEM)/central timer module (CTM) must be reconfigured upon replacement. Refer to the New Generation STAR (NGS) Tester help screen on the Ford Service Function (FSF) card to program the Tire Size, Axle Ratio.
    NOTE: When configuring the GEM, the NGS Ford Service Function (FSF) Card version 1.1 will display the following negative response:
    • UNABLE TO PERFORM TEST/FUNCTION
    • SUB FUNCTION NOT SUPPORTED or INVLID FORMAT
    Ignore the negative response. Although the NGS is generating a negative response, it will successfully configure the tire size and axle size selected.
    Disconnect the battery ground cable (14301).


  1. Remove the radio chassis (18806); refer to Section 415-01.

  1. Remove the center instrument panel finish panel.
    1. Remove the screws.
    1. Remove the center instrument panel finish panel.


  1. Remove the generic electronic module (GEM)/central timer module (CTM).
    1. Remove the screw.
    1. Disconnect the four connectors from the GEM/CTM.
    1. Remove the GEM/CTM.

Installation

  1. NOTE: When the battery (10655) is disconnected and reconnected, some abnormal drive symptoms may occur while the vehicle relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 mi) or more to relearn the strategy.
    To install, reverse the removal procedure.
 
Last edited:

Earl43P

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Please describe the "dash lights" part of your issue.
Reason I say that is there are no dash illumination light circuits in the GEM.

There ARE dash indicator lights controlled by the GEM.
Seat Belt, Door Ajar, 4Hi, 4Low are the ones I see in the 2000 schematic.

Since you did mention a speedometer problem, I can tell that yours is a 2wd. That means that the tire size for speedo cal. IS stored in the GEM, meaning Ford WOULD have to input that value into your new GEM.

The very first thing you should do is clean up the grounds located behind the Parking Brake kick panel and its mate on the passenger side. Should find 3 ground points total, G200 and G203 on the driver side below the fusepanel and G201 on the passenger side.

I also see that the Power Windows Master Switch (driver side) uses G203. The wipers do not have a ground in common (uses G103, located top center of the LH inner front fender).
 

det107

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Please describe the "dash lights" part of your issue.
Reason I say that is there are no dash illumination light circuits in the GEM.
I'd like to chime in that my tach & speedo lights are very dim. The bulbs were replaced & nothing happened-
 

Partwerks

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I have a 1995 Ranger, and replaced the CTM with another one from a junk yard, but didn't solve the problem. Cleaned all the grounds I can think of.

Randomly, I will get a phantom wipe, only when I go to start it. Then the wipers and dome light won't work??

If I unplug the #27 fuse, or unhook/hook the battery back up, it must reset it, and all works, till it decides to do it again?

Are there any grounds by the E brake also?
 

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