What's the difference between the following two Bosch ECU's found in 83 240's with B23F engines and automatics. I've got two 83's purchased new with different ECU's.

83 244GL = 0 280 000 503 (VIN YV1AX8843D2887085)
83 245DL = 0 280 000 510 (VIN YV1AX8852D1491941)

I also noticed the ECU connector plug for the DL has a black wire on Pin 19 and the GL does not. Either ECU box works in either vehicile. jp

Rumor has it that the 510 was an upgrade from the 503 and, along with the provision for a heated O2 sensor, has more robust circuitry in selected spots.

I pulled a 510 from an 84 and put it in place of the 503 that has performed just fine in our 83 (built 10/82) for over 21 years. Absolutely no difference that I can tell...works just fine without a heated O2 sensor.

Our 83 has VIN: YV1AX8847D1835044, so it looks like your sedan may have been a very late 83 model. Since even at that later build date it has a 503, this suggests that the 510 in your wagon was swapped in at some point. The presence of a black wire to pin 19 on the ECU is interesting! My 1983 wiring diagram (factory Green manual) does not even show a pin 19 in the diagrams displaying ECU connections. Pin 18 powers up the ECU via a Blue-Red wire from the fuel pump relay when the ignition is switched on, and pin 20 is the signal from the O2 sensor....but no pin 19 shown.

AFAIK, the exact same ECU was used in manuals and automatics.
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Bob (81-244GL B21F, 83-244DL B23F, 94-944 B230FD; plus grocery-getter Dodge minivan, MGB, and numerous old motorcycles)

The 503 is the correct ECU for '83.

The 510 is proper for a late '84 that came with a 3-wire o2 sensor. Why it's in your '83, I can not say.

The 510 is proper for a late '84 that came with a 3-wire o2 sensor. Why it's in your '83, I can not say

Maybe it was swapped in somewhere along the line. The O2 heater wires are external to the ECU anyhow. And since the CU 91X rebuild covers both 503 and 510, don't you think he's he's probably OK?
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Bruce Young,
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Can't say about internal differences, but both Bosch numbers cross to CU-91X, which is the ECU - Exchange # for '83, '84. (From 1992 Bosch catalog)
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Bruce Young,
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.