This is the schematic of the 87/88 TC IRCM, as traced from the printed circuit board. The circuit all makes sense so I believe that this is 100% correct. In addition to the Jpeg image above, the schematic has also been included as an Adobe PDF file, and may be downloaded by clicking on THIS link. The PDF has better resolution and will also print better.
R2 Zero ohm jumper
R3 130K, 1/4W precision resistor
R4 31.5K, 1/4W precision resistor
R5 1K, 1/4W resistor
R6 62 ohm, 5W resistor
R7 1.5K, 1/4W resistor
R8 -none-
R9 68.2K, 1/4W resistor
R10 1.5K, 1/4W resistor
R11 100K, 1/4W resistor
R12 4.7K, 1/4W resistor
R13 -none-
R14 4.7K, 1/4W resistor
C1 0.01uF, 50V chip capacitor*
C2 -none-
C3 1uF, 63 volt electrolytic capacitor
C4 47uF, 10 volt electrolytic capacitor
C5 0.01uF, 50V chip capacitor*
* The operation voltage has be estimated from the circuit it is used in. Higher voltage capacitors may be subsituted without problems,
D1 *
D2 *
D3 -none-
D4 *
D5 *
*Diode requirements have been estimated from the circuitry. 1N4003 should work in all cases without problems.
Q1 *
Q2 *
Q3 Have yet been unable to determine parameters
Q4 *
Q5 *
Q6 *
* 2N2222A or similar transistors should function well in all these locations. The transistors in the IRCM use a part number that is completely unfamiliar.
Relays are all SPST with 40 amp comtacts, 12 V coils. Bosch number on relay is 0 332 014 162.
IRCM Overview
Disassembly & Reassembly
Theory of Operation
Article text, drawings and photos © 2004 by D. Joseph Frazier and
Rustec Applied Technologies; All Rights Reserved.
DISCLAIMER
Please note that while I've been as careful as possible with this article,
it may contain mistakes. I assume no liability whatsoever for any
detrimental effects using this information may cause to you or your vehicle.