In this tutorial, I'll show you how to resistance test the Under-Drive Shift Solenoid, to see if it's bad and thus lighting up the check engine light with a diagnostic trouble code (DTC) P0765 or a Code 42 (if your Chrysler vehicle is OBD I equipped).
If you're wondering where the heck the Under-Drive Shift Solenoid (also know as Shift Solenoid D) is, this bad boy is inside the transmission's solenoid pack.
Contents of this tutorial:
- Symptoms Of A Bad Under-Drive Shift Solenoid (DTC P0755).
- What Tools Do I Need?
- Where To Buy The Chrysler Solenoid Pack.
- Circuit Descriptions Of The Chrysler Transmission Solenoid Pack.
- TEST 1: Under-Drive Shift Solenoid Resistance Test.
- Under-Drive Shift Solenoid Test Conclusion.
- Chrysler Transmission Solenoid Pack Tutorials.
Symptoms Of A Bad Under-Drive Shift Solenoid (DTC P0755)
When the Under-Drive Shift Solenoid (also known as Shift Solenoid D), inside the transmission solenoid pack, goes bad, you're gonna' see these specific symptoms:
- The check engine light (CEL) will be lit.
- One the following codes in memory:
- P0765: Under-Drive (UD) Solenoid Circuit Malfunction (OBD II equipped only).
- P0765: Shift Solenoid D Malfunction (OBD II equipped only).
- 42: Under-Drive Solenoid Circuit (OBD I equipped only).
- The Transmission will not shift gears:
- More specifically, it'll stay in 2nd gear no matter what speed you're driving the vehicle.
- This is called in tech terms: Limp In mode.
Testing the Under-Drive Shift Solenoid (Shift Solenoid D) is not hard, and in this tutorial, I'll show you how to do it. If the Under-Drive Shift Solenoid is fried, you'll need to replace the entire transmission solenoid pack.
What Tools Do I Need?
A scan tool is a handy (and a must have) tool to read diagnostic trouble codes and view some of the Live Data parameters it provides, but you don't need one to test the Under-Drive Shift Solenoid.
The most important tool that you're gonna' need is a multimeter. Your multimeter can either be a digital multimeter or an analog multimeter.
Here are some of my suggestions:
- Multimeter
- Don't have one or need to upgrade your analog multimeter to a digital multimeter, check out my recommendation here: Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (Amazon affiliate link).
- Scan Tool
- As I mentioned above, you don't need to use a scan tool to take advantage of the test info in this tutorial, but it does come in handy to read any trouble codes.
- If you don't own a scan tool yet, I recommend taking a look at this one: ZM301 OBD2 Scanner Diagnostic Tool (Amazon affiliate link).
- Basic hand tools
- These are: ratchet wrench, sockets, etc., that you'll need to disconnect the solenoid pack's electrical connector and remove and replace the solenoid pack if it's bad.
Where To Buy The Chrysler Solenoid Pack
Your local auto parts store (like AutoZone or O'Reilly Auto Parts) will carry the Chrysler Solenoid Pack (or will be able to order for you). At your local auto parts store, the solenoid pack will cost about US$150 to $200, which is quite expensive.
Another alternative you may want to explore, is buying it online and saving a few bucks. Below, you'll find two links (to the same place) so that you can shop and compare and see what option is best for you!
Disclosure: As an Amazon Associate, I earn from qualifying purchases. Buying through these links helps support this site at no extra cost to you. Thanks for your support —it really means a lot!
Circuit Descriptions Of The Chrysler Transmission Solenoid Pack
Since the Under-Drive Shift Solenoid (Shift Solenoid D) is inside of the transmission solenoid pack, we need to know which to pins to test. These pins are the ones that belong to the solenoid pack itself and not its connector.
The Transmission Solenoid Pack has a total of 8 circuits (pins), and the 2 that we're interested in are pin #4 and pin #5.
Pin #4 feeds power to the Under-Drive Shift Solenoid. Pin #5 feeds the activation signal. These are the two pins that we're gonna' test (with the solenoid pack's electrical connector disconnected).
| Chrysler Solenoid Pack Connector Pin outs | ||
|---|---|---|
| Pin | Wire Color | Description |
| 1 | Yellow w/ Black stripe * | 2-4 Pressure Switch |
| 2 | Dark Green * | Low/Reverse Pressure Switch |
| 3 | Orange w/ Black stripe * | Overdrive Pressure Switch |
| 4 | Red * | Power (10 to 12 Volts DC) |
| 5 | Pink * | Underdrive (UD) Solenoid |
| 6 | Brown * | Overdrive (OD) Solenoid |
| 7 | Light Blue * | Low/Reverse Solenoid |
| 8 | White * | 2-4 Shift Solenoid |
* Your specific Chrysler, Dodge, Plymouth vehicle may have different colors.
One last thing before we move on to the next page (and start testing), the solenoid pack will have the above 8 numbers embossed on it. This will further aid you in identifying the metal male terminals you'll need to test in the next page.
TEST 1: Under-Drive Shift Solenoid Resistance Test
As mentioned in the previous page, the 2 pins (of the transmission solenoid pack) that we need to test are pins #4 (power circuit) and #5 (activation circuit). These 2 pins are the ones that will complete the circuit of the Under-Drive Shift Solenoid.
Remember, the Under-Drive Shift Solenoid has to be tested with the solenoid pack's 8-wire connector disconnected.
NOTE: If the engine/transmission is hot, let it cool down. It's best that you do this test with a cold engine or you run the risk of getting burned by a hot engine and/or Transmission. Be careful, use common sense and think SAFETY.
OK, this is what you'll need to do:
- Disconnect the solenoid pack from its 8-wire electrical connector.
- This is an on-car test, so you don't have to remove the solenoid pack to test it.
- If you've already removed the solenoid pack from the transmission -wells that's cool too, the test instructions still apply.
- Set your multimeter to Ohms mode.
- With the red multimeter test lead, probe the metal male terminal labeled with the number 4 in the photo above.
- With the black multimeter test lead, probe the metal male terminal labeled with the number 5.
- Your multimeter should register between 0.5 to 9 Ohms.
Let's take a look at what your test result means:
CASE 1: The multimeter registered the indicated Ohms. This is good and confirms that the Under-Drive Shift Solenoid (within the solenoid pack) is OK.
Since a trouble code P0765 is lighting up the check engine light on your instrument cluster, the next steps are:
- Check the continuity of circuit #5 between the Transmission Control Module and the solenoid pack's connector.
- Check the physical condition of the solenoid pack's connector and the round metal terminals inside of it for damage.
The above steps are beyond the scope of this article, but at least now you know what direction your troubleshooting needs to take.
CASE 2: The multimeter DID NOT register the indicated Ohms. Double check that you're testing the correct metal male terminals on the solenoid pack and retest.
If you still don't see the indicated resistance in Ohms, then the Under-Drive Shift Solenoid is bad. You'll need to replace the solenoid pack assembly to resolve the problem.
Under-Drive Shift Solenoid Test Conclusion
Sooner or later, every Chrysler vehicle on the road will need to have the solenoid pack replaced. I've replaced many over the years (working as diagnostic tech in an automotive repair shop). So, in this section, I want to share a couple of personal suggestions that I think will help you:
- Whenever any of the shift solenoids, inside the solenoid pack, go bad, the transmission will go into LIMP IN mode. This means the transaxle will stay and run in 2nd gear only.
- A bad Under-Drive Shift Solenoid (Shift Solenoid D) will not cause your transmission to slip.
- If your vehicle's transaxle is slipping, then replacing the solenoid pack will not help since slippage is a direct result of internal transaxle damage (burned clutch discs, broken/worn internal hard parts, etc).
- Can a bad solenoid pack cause the transaxle to go bad?, the answer is YES if you don't take care of the problem as soon as possible and/or continue driving it for extended amounts of time/distance in LIMP IN mode.
- When reconnecting the solenoid pack's electrical connector, don't tighten it to death or you'll strip the threads or break the solenoid pack.
Well, in conclusion: I hope this test tutorial helped you. If it did, drop me a line using the contact form below. Sharing your diagnostic and repair experience will definitely help other readers facing the same issue/dilemma.
Chrysler Transmission Solenoid Pack Tutorials
The following tutorials relate to this transmission solenoid pack tutorial:
- Testing Diagnostic Trouble Code P0750 (Low Reverse Shift Solenoid Malfunction).
- How To Test Diagnostic Trouble Code P0755 (2-4 Shift Solenoid Malfunction).
- How To Test Diagnostic Trouble Code P0760 (Overdrive Solenoid Malfunction).
If this info saved the day, buy me a beer!
