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Discussion Starter #1
I need a way to read the A604 fault codes. My dealer can not do it as they no longer have the legacy DRBII to scan. They don't even have the connector to the SCI diagnostic port. My A604 is in "Limp" mode. I have several scan tools that will read the engine codes, but none will read the transmission codes. OH! by the way the vehicle is an 1989 Dodge Grand Caravan (has antique tags). Because the miles on this A604 are about 13K, and the vehicle is 31 years old, and the wiring is 31 years old, I am leaning towards a wiring problem such as the infamous "Red wire splice", or maybe a ground connection is faulty.
Just would like to know if there are any codes that might direct my repair search.
 

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I have run into a similar problem with my -98 Durango and abs faults.
- it seems like the holy grail for keeping a pre can bus (2004...2006) mopar is a drb3.
Ive search high and low but havent beeen able to find a substitute that gives non obd functions.
 

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. . . I need a way to read the A604 fault codes. My dealer can not do it as they no longer have the legacy DRBII to scan. They don't even have the connector to the SCI diagnostic port. . . . .
You can still find a Chrysler OBD I to OBD II interface connector. Internet search on "Chrysler OBD I to OBD II connector." The problem is finding an early 1996 or later OBD II scan tool that could interface and communicate with the first generation transmission control module.

. . . Just would like to know if there are any codes that might direct my repair search. . . .
Attached is a list of 13 possible transmission diagnostic codes for 1989 A604 transmission. For each code there are numerous elements that could be generating the fault code.

A604 Diagnostic Codes 1989 Year.gif

As a start you could remove and check the electrical connector at the TCM (transmission control module). Check for dirt, corrosion, etc that could interfere with a proper electrical signal between the TCM and engine control module.
 

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The first half of this article covers the PCM connector. The second half covers the Body connector which is the one for reading TCM codes.
OBD-I compatibility issues and solutions (at https://chryslerccdsci.wordpress.com/2019/09/11/obd-i-compatibility-issues-and-solutions/ )

There should be obsolete scan tools for sale out there that are capable of reading Chrysler CCD bus data. The DRB II was the scan tool used in 1989. The later DRB III could do pre-'94 vehicles when a Supercard was used.

This DRB II says "with cords and case", but they aren't shown. You could make up a Body cord if necessary.
Chrysler Motors DRB II Diagnostic Unit Cartridges Cords Case | eBay (at https://www.ebay.com/itm/Chrysler-Motors-DRB-II-Diagnostic-Unit-Cartridges-Cords-Case/153430482463?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D225086%26meid%3Dbd9c357881904a218e3694c38abec63d%26pid%3D100667%26rk%3D1%26rkt%3D1%26mehot%3Dnone%26sd%3D153430482463%26itm%3D153430482463%26pmt%3D0%26noa%3D1%26pg%3D2334524&_trksid=p2334524.c100667.m2042 )

I have not done business with this seller.

Make sure that you have the latest and greatest software version in your TCM and use ATF+4 for best results. A TSB # 18-24-95 was the fix for many issues.
The TCM part # for a 3.0L should be 4796121.
 

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I had great luck with a SnapOn MT2500. It's an old tool, so you can sometimes get them inexpensively. But it can get expensive if hey don't come with all the parts. You'll need the domestic cartridges, Chrysler 1 and Chrysler 2 connectors (for OBDI) and the proper personality keys (usually 13 or 13A) for OBDII Chrysler products.

I've had one for over 10 years. OBDI engine diagnostics, transmissions, ABS, body codes,etc.
 

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Discussion Starter #6
Here is my approach, with out any codes, is to check continuity on all of the wires from the solenoid control connector to the 60-way connector on the TCM. Take the loom apart to fine the 'infamous" splice and check for opens and shorts. I will check the EATX relay (which has many names such as Safety Shutdown Relay). Clean all the terminals in the various connectors. I am going the change out the Solenoid Control Module connector. After all of that replenish the ATF+4 to operating lever. I might throw in replacing the Solenoid Control Module before adding the ATF+4.

I did find that a mechanic at a local Master Tech Automotive that has a 20+ year Mopar Tech that still has his own test equipment, so I might get him to run diagnostics on my A604 ($90+ for the service time)
 
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Discussion Starter #8
I will take your advice on that. I had actually tried to do that, but my dealer no longer has the legacy DRB-II and SCI connector, so I got no codes.
 

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Discussion Starter #9
Where is the EATX diagnostic connector actually located? I have looked around under the steering column, but have not found it yet. In fact is was today that I learned that the transmission codes are read through this CCD diagnostic connector, and I did not even know it existed. I found it in my wiring diagrams in my Shop Manual, but it does not identify its location.
 

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. . . Where is the EATX diagnostic connector actually located? I have looked around under the steering column, but have not found it yet. In fact is was today that I learned that the transmission codes are read through this CCD diagnostic connector, and I did not even know it existed. . . ..
The diagnostic link connector moved under the steering column with 1996 and later models which are OBD II. Your 1989 model is OBD I. Its connector is located near a row of relays mounted on the left front inner fender apron and near the left front shock tower.

In the 1988 factory service manual it shows the connector on page 14-50 (multipoint fuel injection) but this may not be the same page in a 1989 service manual.
 

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The lack of drb1-3 replacements will ultimately kill mopars from late 80´s to early 2000`s.
 

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It is under the driver's lower dash panel. It may be on the lower ledge or tucked into the harness near the brake pedal (if it had never been accessed).
Look for this connector (it won't be plugged into anything):



The one out under the hood is for the PCM engine controller only, not the TCM.
 

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The lack of drb1-3 replacements will ultimately kill mopars from late 80´s to early 2000`s.
There are aftermarket options.
 

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Discussion Starter #15
Thanks. I knew the SCI was under the hood, used it many times. It was the CCD bus diagnostic connector. Thanks ImperialCrown for the info. That is a drawing of the CCD buss connector (Body Cable Connector) I am looking for.
I think because it was new with the 1989 vehicles with the new EATX, the shop manual was not updated to show the location. Lucky it is shown in the wiring diagrams for the 3.0-L with EATX so I knew it was the transmission code gateway.
 

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I just popped over to eBay and looked around. With careful shopping you can get an OBDI capable tool to read transmission, engine, abs codes for less than $200.
You just need to make sure the cartridge covers the Chrysler years you need and you need CHRY-1 and CHRY-2 adapters for the cable.
Like this scanner with cartridges:
SNAP-ON DIAGNOSTICS SCANNER MT2500 BUNDLE | eBay (at https://www.ebay.com/itm/SNAP-ON-DIAGNOSTICS-SCANNER-MT2500-BUNDLE/324056700317?hash=item4b7348d59d:g:DfQAAOSwmHBeHde2:sc:USPSFirstClass!15642!US!-1 )
But you'd also need these Chrysler OBDI cable adapters:
Snap-on MT2500-31 MT2500-30 CHRY-1 & CHRY-2 Scanner Adapter | eBay (at https://www.ebay.com/itm/Snap-on-MT2500-31-MT2500-30-CHRY-1-CHRY-2-Scanner-Adapter/133109504103?epid=1411827082&hash=item1efdf1d867:g:xXgAAOSw1UdcrVPZ )

I hate to say this, but I would not assume a 1989 transmission is fine, and the issue is only electronic, even if it is a low mileage unit.
 

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There are aftermarket options.
- Like?
I´ve been trying to find something that reads abs codes on a 98 Durango and the only thing i´ve found is 3000$ drb3´s.
I seriuosly doubt that a witech with a drb3 emulator can do it since it seems lika a can bus only unit and the usual obd2 functions.
 

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It is under the driver's lower dash panel. It may be on the lower ledge or tucked into the harness near the brake pedal (if it had never been accessed).
Look for this connector (it won't be plugged into anything):



The one out under the hood is for the PCM engine controller only, not the TCM.
IC: On my 92 with the 4 speed I have a connector under the steering wheel which is for the trans. The connector under the hood is for the engine ecu.
 

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- Like?
I´ve been trying to find something that reads abs codes on a 98 Durango and the only thing i´ve found is 3000$ drb3´s.
I seriuosly doubt that a witech with a drb3 emulator can do it since it seems lika a can bus only unit and the usual obd2 functions.
I’ve lost count of the times I’ve mentioned the SnapOn MT2500.
Check it out, it supports ABS on many OBDI vehicles. I used it on my 94 LeBaron and 95 Neon ABS.
My Dakota only had rear ABS and I never tried it (or had a reason to).
 

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I know that it nice being armed with all the necessary tools, but you have to weigh the benefits of purchasing an advanced scan tool against a shop diagnostic charge. If you know someone with an advanced tool that will let you rent or borrow it, then you are ahead of the game.
If you will be using the scan tool just a couple of times to diagnose one or two issues, it may not be worth the cost and may not pay for itself.
A repair shop can purchase a scan tool costing several thousand dollars because it gets used daily and can eventually pay for itself.
The OBD1 needs the Chrysler-specific software and connecting cable from over 25 years ago. The tools lasted a long time, but the cables usually got damaged and worn from hard use.
 
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