Isuzu SUV Forum banner

98 Amigo antilock

32K views 58 replies 6 participants last post by  alanb21 
#1 ·
The antilock warning light on my 98 Amigo is on most of the time. A friend of mine has a code reader which indicated ALL antilock codes being set. He was not able to reset codes. Any ideas?
 
#2 ·
Do you have the owners manual? The first thing to try is the process in the manual. It says to drive a certain distance under a certain speed to shut the ABS light off. Mine was on for a couple days once after braking hard to avoid an accident, i did what the manual says and it went right off.
 
#4 ·
The usual reason for an intermittent ABS warming lamp on a 2nd gen Rodeo/Amigo is a open circuit in the wire harness going to the rear ABS sensor. It typically breaks where the harness makes the transition from the left rear trailing arm to frame. As the rear suspension moves up and down it flexes the cable causing it to break. It is in a difficult spot to for a repair. Most people, including me, just pull the ABS fuse to deactivate it.
 
#6 ·
Buster28;
I finally got a chance to go under the vehicle on a creeper. I found a 3 wire connector above the left rear corner of the gas tank. If that is an antilock connector (H-26), it appears to be difficult to get at without removing the tank. I may bypass this section of wire with a shielded cable. Any thoughts (besides I'm crazy)?
Alan
 
#7 ·
#8 ·
Pop the harness tie downs loose (a couple are difficult but do-able) and there is enough room to work with. I just cut the plug off and soldered in some longer lengths of wire on mine. Not sure the replacement harness really does much after the fact since it's usually on the main harness side of the plug that the wires get ripped out.

My original write up on it. It later broke again and thats when I just cut the plug off and hardwired it. Fine since then.
viewtopic.php?f=1&t=56236&p=476995
 
#10 ·
If want to do some actual troubleshooting to locate the open circuit you can remove the 16 pin electrical connector from the EBCM located on the right inner fender. Measure the sensor resistance across pins 4 and 12 which should be about 2K ohms. If it reads open, start moving the harness until you get a reading. Btw, you don't have to clear ABS codes, the ABS warning lamp will turn Off when vehicle speed is greater than 8mph if the fault has been repaired.
 
#11 ·
Hi Buster,
The lower connector at the EBCM has two rows of contacts. One is marked A1 to A8 while the other is marked B1 to B8. Do I presume that A1 is pin 1, while B4 is really pin 12 of connector C-4? If so, I can disconnect the rear sensor, jumper pins 4 and 12 and use an ohmmeter to find the open. I am working by myself on this project and find it very difficult to monitor the meter at the front of the vehicle while I'm laying under it :).

Alan
 
#12 ·
You could jumper 4&12 and look for continuity across the sensor connector pins or make a long set of meter leads using lamp cord. Use appropriate size probes to prevent damage to the connector pins. The image is harness connector that you would measure or jumper.
 

Attachments

#13 ·
I managed to pull the harness down below the gas tank. No broken wire detected. The resistance from the EBCM connector pins 4 and 12 is currently at 1275 ohms.
My plan of attack for tomorrow is to reconnect everything, clear the codes and see what returns. It is entirely possible that I am chasing the wrong fault. Good thing I'm not flat-rate Actually I'm not even hourly. I am, however, retired.

Alan
 
#16 ·
The ABS EBCM runs a self check every startup so I would assume all failure codes are current. I don't believe it creates a failure history like the ECM, it it does my scan tool can't retrieve it. Btw, you can test the wheel speed sensors by measuring the ACmV across the connector pins as you rotate the wheel by hand.
 
#17 ·
Unfortunately my Harbor Freight VOM cannot read ac voltages that are in the millivolt range. I'm waiting for a friend of mine to get back to me as to the availability of a meter.
Can I hardkey the ALDL connector to flash codes, or do I need a scan tool?

Thanks for your help.
Alan

P.S. I measured the resistance from connector C-4. The rear sensor read 1344 ohms while both front sensors were 2.34 in the 20K scale.
 
#18 ·
You can enable the ABS flash code diagnostic by grounding Pin 12 of the DLC. Pin 4 and 5 of the DLC are ground.
Most scan tools can't read Isuzu ABS codes but an Innova 3160 can, $199 at amzn.
The resistance values are as expected, so it it not likely any of the wheel sensors are defective. However, the front wheel segmented " tone rings" are sometimes left off during a brake rotor change which disables the sensor. Also, the segments can get clogged with rust or the sensor probe can be rusted which also functionally disables the sensor .
 
#20 ·
I was able to take voltage readings from all three sensors. Depending on vehicle speed (wheels off the ground and in 4wd), the voltage was up to 1.7 volts ac. So, I hardkeyed the ALDL connector. 11 codes are being produce. 61, 62, 22, 41, 43, 45, 46, 42, 44, 15 and 35. Multiple attempts to clear the codes only resulted in them returning. Am I missing something, or do I have an EHCU (EBCM) that is intermittently (but rarely) good? Poor ground?
 
#21 ·
The DTCs you listed translate into these failures:
Low or High Ignition Voltage (DTC 15)
Brake Switch Failure (DTC 22)
EHCU Valve Relay Failure (DTC 35)
FL Speed Sensor Missing Signal (DTC 61)
FR Speed Sensor Missing Signal (DTC 62)
FL Isolation Solenoid Coil Failure (DTC 41)
FL Dump Solenoid Coil Failure (DTC 42 )
FR Isolation Solenoid Coil Failure (DTC 43)
FR Dump Solenoid Coil Failure (DTC 44)
Rear Isolation Solenoid Coil Failure (DTC 45)
Rear Dump Solenoid Coil Failure (DTC 46)

DTC 15 Low or High Ignition Voltage could be the actual problem if the ABS Warning Lamp is intermittent.
High voltage could be an alternator problem and Low voltage could be an ABS module ground problem.
 
#23 ·
Forgot to mention that the previously replaced alternator was generating an ac signal as evidenced by the batt warning light flickering.
Measured good grounds at c5-2 and c4-7. used a test light as well as vom. Also checked inputs at c4-1, 6 and 13.
Don't think that I am going to like any answer posts to follow.
Alan
 
#24 ·
The ABS draws a lot of current which is why it is fused at 60 Amps, so make sure the electrical system is not the source of the problem.

If you are 100% sure there is not an intermittent open circuit in the wiring to the EHCU the only thing that can cause all those error codes to be generated at the same time would probably have to be an open circuit on the Coil Integrated Module (CIM) involving the power. Since the fault is intermittent there must be a crack in a foil or a cold solder joint which you may be able to locate with some luck. I have never actually removed the CIM from a Rodeo but you should be able to remove the CIM assembly without disturbing the hydraulics, it is secured to the hydraulic unit with four screws. You can drive the vehicle with the CIM removed, it is not mechanically attached to the hydraulic valves.

If you want to disable the system you can leave the C-4 disconnected and if you want to turn off the ABS lamp insert a piece of thin plastic between the spring loaded jumper that shorts pins 6 and 7 together when C-4 is disconnected. The plastic isolates the ABS lamp ground which disables the lamp.
 
#25 ·
Removed the CIM this am. Now have to purchase a Torx driver small enough to remove the case screws. It appears to be a Kelsey-Hayes 325. The P/N on the label is 897263882. E-bay has one listed but says it is not compatible with the Amigo. I wonder if the module was replaced before I purchased the car. The other number on the label is 155S575. I guess a call to Isuzu is in order.
I also found this http://modulemaster.com/en/abs/kh_325.php. Interesting site.
I'll post again later today.
It's now later in the day. I called Isuzu. The above number 897263882 has been superceded by 8973577000. The original one should work if it is good. The cover is sealed to the phenolic body by what appears to be a silicon gasket.
Also tested the pump operation via jumper to battery (thru circuit breaker). Pump ran when commanded to do so. Monitored the 12 volt and ground (main) at the C-5 connector while moving wires around. No variation noted on vom.
I also noted that my schematic from AllData does not show the pump or its connector.
Alan
 
#26 ·
If you decide to get a replacement CIM be aware there a 2WD and a 4WD version of the module. I am reasonably sure the 4WD version is 8973577000 (Isuzu/Honda part # 8-97357-700-0) and the 2WD version is 8-97357-701-0
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top