1998 D1 4.0 ECU

skewed

Member
Jul 26, 2021
8
0
st. louis missouri
i have a 98 D1 and i was told the idle issue (revs up in park and neutral) was due to a fault with the ECU.

are ECU’s swappable ? my friend has a spare but i’ve read that they are not interchangeable but i’ve also read another ECU will “learn” the correct values for your truck with a couple of drive cycles. i could also get one from Will that is flashed but don’t know if that will work??
 

Flyfish

Well-known member
Oct 29, 2004
1,275
144
50
St. Louis
my friend has a spare but i’ve read that they are not interchangeable
All 97-99 D1 4.0 Gems ECU‘s are interchangeable. Only factor is AEL vs non-AEL trucks.

But trying a spare will tell you if your ECU is the problem if the high idle goes away or not. If it doesn’t go away with the test ECU, then it’s something else.
 
Last edited:

skewed

Member
Jul 26, 2021
8
0
st. louis missouri
All 97-99 D1 4.0 Gems ECU‘s are interchangeable. Only factor is AEL vs non-AEL trucks.

But trying a spare will tell you if your ECU is the problem if the high idle goes away or not. If it doesn’t go away with the test ECU, then it’s something else.
cool. thanks todd !