4L30E Pump Interchange Part II

4L30E Pump Interchange Part II: Ending a Myth

PLAYING WITH FIRE

4L30E Pump
Interchange Part II: by Jon Rodriguez

Ending a Myth

S ince the first edition of Playing
with Fire in the July, 2008
GEARS, there have been a lot
of questions about the interchange and
whether it really works. Claims of too
formed correctly. We’ll address each of
these concerns, one at a time.

Complaint 1: Firmer TCC
Apply
4L30E applications as long as you
install the capsule. The firmer apply
shouldn’t become an issue as long
as you inform the customer before-
hand. Remember, you’re doing this
firm of a lockup apply, codes P0742, Starting with the firm TCC apply: changeover for customer savings. Let
P1870, and a cycling lockup have been yes, the apply will be firmer than the them decide whether it would be worth
circulating through other well-respect- original setup, but not abnormally doing.
ed technical firms. One suggested that harsh… as long as you install the ori-
the changeover could cause all four of ficed checkball in the input shaft. The Complaint 2: Code P0742
these problems. PWM version does not use the orifice The next concern is a code P0742
In this edition of Playing with Fire Checkball to control lockup feel. The — TCC system stuck off. Figure 1
we’re going to go into a little more TCC apply can be brutal if you don’t shows the conditions that will cause the
detail about the system and show how install the capsule. The apply will feel PCM to set code P0742 and is a copy
this changeover works… when per- the same as an on/off setup in other from the 2002 Isuzu service manual.

12 GEARS January/February 2009

Figure 1

GEARS January/February 2009 13


Order a 4L30E Solenoid
(P/N 8-96042-666-0) or install the
lighter TCC control valve spring from
the PWM application.

Figure 2

Of the 13 conditions the PCM is look- the changeover itself. We’ll go into the the on/off changeover. Unfortunately
ing for — only the ninth and eleventh specifics of this a bit later. we didn’t discover this trend until after
conditions have anything to do with printing the first article.
command and slip speed: Complaint 4: TCC Cycling So how can you avoid this condi-
9 — TCC is commanded off. This is by far the most common tion? Order a genuine 4L30E solenoid
11 — TCC slip speed is between 20 complaint and usually occurs at light from your local parts distributor. By
and 40 RPM for 2 seconds. throttle. Most of us have diagnosed the way, the OE part number is: 8-
In terms of this changeover, the P1870 codes in applications that are 96042-666-0. Or install the lighter TCC
code would occur if the PCM com- generous with data and have seen that control valve spring from the PWM
manded lockup but the transmission normal TCC slip is 0-10 RPM with application (figure 2). Either of these
didn’t respond. We’ve found that this 40-70 percent duty cycle, depending solutions eliminates the TCC cycling at
condition is due to a faulty TCC sole- on load and the integrity of the TCC light throttle.
noid or pump, rather than the change- circuit; the Isuzu application is no dif- To prevent this from being an issue
over itself. Treat this code as you would ferent. with future changeovers, always install
for unit that had not had the changeover This complaint occurs when the the lighter TCC control valve spring
at all. PCM commands a slip at low speeds from the four-valve pump behind the
and light throttle, but the converter TCC control valve in the two-valve
Complaint 3: DTC P1870 releases entirely. The PCM responds pump. Adding this step to the change-
Now let’s look at the third com- by raising the duty cycle, reapplying over will allow you to use the 4L80E
plaint: DTC P1870 — transmission the converter clutch, and then repeat- solenoid without any problems.
component slipping. Figure 3 was taken ing the process. The root cause of this Many hours of research went into
directly from the 2002 Trooper factory complaint is using a 4L80E TCC sole- this article using information gath-
manual. It shows the criteria for P1870, noid rather than a genuine 4L30E TCC ered from willing members to try this
and again, the changeover won’t meet solenoid. changeover, as well as my own time
any of the necessary conditions for set- The solenoids are the same resis- in developing this interchange. This
ting the code: tance and fit without modification, but changeover has been successful in doz-
10 — TCC slip speed is between the flow characteristics are quite dif- ens of cases prior to the original article,
250 RPM and 800 RPM, 3 ferent under the same command condi- and continues to serve as a viable alter-
times for 7 seconds. tions. It takes a higher duty cycle for native to replacing a worn out PWM
13 — ECCC is on. the 4L80E solenoid to allow the same pump assembly with the over-priced
Provided that the converter, pump, amount of flow under the Trooper’s replacement.
and TCC solenoid are functioning PCM signal. Many parts distributors I hope this clears up any doubts
properly this changeover eliminates the carry the 4L80E solenoid as a replace- you may have about this changeover,
potential for TCC slip. Here again, ment for the 4L30E, and it’ll work fine and find the information useful for
look for faulty components rather than in the earlier on/off units but not with building better units.


In These Uncer tain Times
It ’s Good to
K now you c an
st ill Count on
Slauson

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Figure 3

FINDINGS: During my research for this article, I on a 2000 Trooper with a freshly-built transmission with a rebuilt
measured the amount of force necessary to move the TCC control converter. I used a graphing meter connected directly to the sole-
valve to the locked position in both PWM and on/off applications. noid signal wires; it revealed full TCC occurred at around 50%.
Both valves have identical surface area (0.12 square inches) on the I then used a solenoid dyno to test the flow characteristics of
control side, so the spring weight is the critical difference. The PWM the PWM solenoid and found that, with 100 PSI of line pressure —
TCC control spring has a working weight of 2.5 lbs; the on/off control which is normal cruising pressure for these units — it took 40% duty
spring is 4.5 lbs. cycle to let 50 PSI reach the control valve. At 90 PSI, as stated in
Based on these spring weights, the PWM needs 20.83 lbs of the original article, it took 45%. These percentages are satisfactory
force to move the TCC control valve into lockup position; the on/off to the PCM programming and we’ve had several ATRA Members
needs 37.5 lbs to shift the valve. perform this modification with no problems.
Then I measured the duty cycle controlling the TCC solenoid


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